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QP55  .G98  Contributions  to  pra 


RECAP 


CONTRIBUTIONS 


TO 


PRACTICAL  PHYSIOLOGY 
AND  PHARMACOLOGY 


BY 


CHARLES  CLAUDE  GUTHRI^ 

Professor  of  Physiology  and  Pharmacology 
University  of  Pittsburgh  Medical  School 


1915 


College  of  ^fjpgicianj;  anb  burgeons 
Hibrarp 


Digitized  by  tine  Internet  Archive 

in  2010  witii  funding  from 

Open  Knowledge  Commons  (for  the  Medical  Heritage  Library  project) 


http://www.archive.org/details/contributionstopOOguth 


CONTRIBUTIONS 

TO 

PRACTICAL  PHYSIOLOGY 
AND  PHARMACOLOGY 


BY 

CHARLES  CLAUDE  GUTHRIE 

Professor  of  Physiology  and  Pharmacology 
University  of  Pittsburgh  Medical  School 


1915 


QP6'5 


Published  and  Presented 

by 

THE  WRITER 


CD 


in 

CTJ 


^  CONTENTS 


Page 

Myograpli     7 

Bath    12 

Muscle  Volume  Tiilie 15 

Weights   15 

Ergograph    17 

Gas  Chamber  Electrodes 17 

Thermal  Electrodes  20 

Cardiograph   22 

Simple  Electrodes    25 

Special  Cardiograph    26 

Frog  Holder.    Form  1 27 

Frog  Holder.    Form  H 27 

Frog  Holder.    Form  III 2S 

Turtle  Holder  rso 

Tuning  Fork    ;!1 

Signal.    Form  1 154 

Signal.    Form  II 35 

Drum  Key  for  Use  in  Primarj'  Circuit 36 

Combined  Rheocord  and  Bridge.    Form  1 39 

Combined  Rheocord  and  Bridge.    Form  II 42 

Combined    Primary    Key   and    Secondary    Cut-out    Key,    Switch    and    Com- 
mutator      43 

Combined    Constant    Contact    Primary    and    Automatic    Secondary    Cut-out 

keys.     Form   1 45 

Combined    Constant    Contact    Primary    and    Automatic    Secondary    Cut-out  . 

Keys.     Form  II 46 

Combined    Constant    Contact    Primary    and    Automatic    Secondary    Cut-'out 

Keys.     Form  II 47 

Multiple    Drum    Stand 47 

Automatic   Myograph   Key 49 

Drum  Contro  Standi    Form  1 51 

Drum  Control  Stand.    Form  II 54 

Recording  Drum  and   Controller 55 

Combined  Primary  and  Secondary  Circuit  Controller 64 

Combined  Coil,  Current  Controller,  Rheocord,  Primary  and  Secondary  Keys, 

Switch  and  Commutator  (Combined  Coil  and  Current  Controllers) 68 


INTRODUCTION 

As  all  nrc  aware  of  the  limited  amount  of  time  provided  for  Physi- 
olog'v  and  Pharmacology  in  the  modern  medical  course,  and  also,  of  the 
nature  and  aims  of  such  courses,  it  is  unnecessary  to  give  lengthy  rea- 
sons for  the  view  that  time-saving  laboratory  methods  are  desirable. 

By  providing  the  student  with  simple,  efficient  and  sturdy  appa- 
ratus designed  especially  to  meet  the  requirements  of  the  courses,  I 
l)elieve  much  time  now  devoted  to  the  purely  mechanical  side  of  the 
experimental  work  may  be  saved,  thereby  enabling  him  to  perform 
more  experiments  in  the  allotted  time.  Also,  his  results  will  be  more 
certain  and  accurate,  and  being  less  burdened  with  mechanical  details, 
his  mind  will  be  freer  to  contemplate  the  physiological  or  pharmaco- 
logical phenomena  revealed  during  the  time  of  the  experiment,  a  j)oint 
I  would  strongly  emphasize.  Finally,  I  believe  that  under  such  condi- 
tions the  courses  would  have  larger  pedagogic  values. 

The  view  has  been  held  that  by  assembling,  adapting  and  devising 
all  of  the  separate  pieces  of  apparatus  for  each  experiment  the  student 
gains  valuable  practical  training,  both  manual  and  technical.  I  believe 
the  value  of  this  feature  of  such  courses  has  been  overestimated  in  the 
past ;  and  with  modern  preliminary  requirements  for  medical  students, 
I  see  no  reason  why  the  Physiologist  or  Pharmacologist  should  deem  it  a 
part  of  his  duty  to  teach  manual  training  or  elementary  physics.  Only 
a  very  small  percentage  of  such  students  become  teachers  or  investi- 
gators in  these  fields,  and  the  course  with  time-saving  apparatus  is  not 
less  stimulating — in  fact,  it  is  more  so. 

From  a  purely  technical  standpoint,  physiology'  has  not  kept  abreast 
of  her  sister  science  physics,  save  in  certain  special  fields.  Even  in 
muscle-nerve  physiology  there  is  no  uniformity  of  methods  in  different 
laboratories.  In  general,  the  student  is  obliged  to  adapt  apparatus  to 
particular  ends.  Therefore,  results  are  secured  at  the  expense  of  much 
time,  and  the  results  themselves  are  prone  to  be  inaccurate.  The 
mechanical  errors  are  great  and  imperfectly  known,  since  for  the  most 
part  such  apparatus  is  not  standardized.  Also,  time  and  the  limita- 
tions of  the  apparatus  render  study  of  the  finer  and  more  ultimate 
phenomena  impracticable.  Pedagogically,  for  the  time  expended,  the 
result  is  unsatisfactory. 

I  believe  that  much  can  be  done  to  remedy  the  condition,  both  by 
individual  teachers  and  by  co-operation  between  schools.  The  material 
presented  in  the  succeeding  pages  is  offered  from  this  standpoint. 
Though  the  task  has  been  very  time-consuming,  the  improvement  in  the 


students'  results  and  the  very  marked  extension  of  the  experimental 
work  rendered  possible  in  the  laboratory  is  abundant  justification.  I 
shall  be  glad  if  others  can  in  any  way  profit  by  it. 

All  of  the  apparatus  has  been  thoroughly  tested,  both  directly  for 
mechanical  faults  and  by  use  in  experiments  for  which  it  is  designed. 
Much  of  it  has  been  used  as  regular  student  equipment  for  one  or  more 
terms,  which  is,  perhaps,  the  severest  test  to  which  apparatus  is  sub- 
jected. In  designing  and  constructing,  the  purposes  and  conditions  of 
its  use  have  been  primary  considerations.  Simplicity  and  durability  of 
design  have  been  retained  at  the  expense  of  accuracy  when  the  difTer- 
ence  in  the  latter  has  been  largely  of  theoretical  importance.  Absolute 
perfection  is  desirable,  but  difficult  of  achievement,  even  in  the  most 
highly  specialized  instruments  and  to  have  striven  for  this  at  the 
expense  of  simplicity,  durability  and  cost  would  have  conflicted  with 
the  plan  under  which  the  work  was  undertaken.  Therefore,  although 
recognizing  its  imperfections,  I  am  convinced  that  when  used  for  the 
purposes  for  which  it  is  designed,  the  apparatus  gives  credible  results 
which,  from  a  practical  standpoint,  are  satisfactory.  The  probable 
errors  and  practical  limitations  are  given  in  most  cases  along  with  the 
descriptions. 

It  is  planned  for  the  second  number  of  this  contribution  to  deal 
with  the  working  directions  based  upon  laboratory  experience  with  the 
apparatus.  The  value  of  such  directions  is  enhanced  by  their  actual 
employment  in  the  laboratory  and  for  this  reason  they  may  not  be 
printed  until  they  have  been  further  tried  out  in  the  regular  course  dur- 
ing the  approaching  session. 

I  shall  welcome  suggestions  both  in  the  way  of  criticisms  and  in 
the  way  of  improvement  of  the  apparatus. 

The  drawings  reproduced  were  made  to  scale  so  that  with  the 
descriptions  and  specifications  any  competent  mechanic  can  construct 
the  apparatus. 

It  is  a  great  pleasure  to  acknowledge  the  helpful  suggestions  of 
past  and  present  members  of  the  departmental  stafif  and  particularly 
the  painstaking  work  of  Mr.  Robert  Tontrup,  mechanician,  and  the 
patient  and  skillful  testing  and  drawing  of  Miss  ]\Iarian  Lee,  research 
assistant. 

Private  publication  was  decided  upon  owing  to  the  policy  of  appro- 
priate journals  of  barring  or  restricting  purely  technical  material.  It 
seemed  most  desirable  to  publish  all  of  the  material  at  one  time  and 
in  one  place. 

July  31,  1915. 


CONTRIBUTIONS  TO  PRACTICAL  PHYSIOLOGY  AND 
PHARMACOLOGY 

PART  I— APPARATUS 

^Myograph 

This  form  of  myograph  is  designed  primarily  for  recording  con- 
tractions in  isolated  skeletal,  cardiac  and  plain  muscle,  but  it  is  also 
convenient  and  efficient  for  studying  muscle  in  situ,  Figs.  1,  2,  and  3. 


Fig.    1.     ^Myograph   assembled   with   drum   stand,   automatic   stimulating  key   and    rheocord, 
hand   primary    key   and   secondary   cut-out   key   and   switcii,    coil,   and   battery. 

It  has  but  slight  inertia.  The  frame  is  of  brass.  It  is  pierced  by  holes 
and  threaded  sockets  for  various  attachments.  The  lever  may  be  used 
as  a  simple  lever  with  both  arms  horizontal  or  as  a  right  angle  lever, 


8 


Myograph 


the  recording  arm  being  horizontal  and  a  short  arm  to  which  the  force 
is  appHed,  perpendicular.  The  lever  is  made  of  thin  brass  tubing 
rigidly  attached  at  the  fulcrum,  Fig  4.  This  point  is  transversely 
pierced  with  a  tube  which  firmly  holds  the  axle  which  turns  in  bearings 
in  the  frame.  The  entire  construction  is  such  that,  though  light,  the 
instrument  is  very  rigid  and  compact.  All  parts  are  readily  accessible. 
The  horizontal  arms  of  the  lever  are  pierced  with  perpendicular 
holes  at  intervals  of  one  centimeter  from  the  fulcrum.  These  holes 
serve  to  mark  centimeter  intervals,  and  as  points  of  attachment  for  the 


QU: 


Fig.   2.     Myograph.      Posterio-lateral  view. 

A.  Frame. 

B.  Lever. 

C.  lyever  rest  or  after-loading  screw. 

D.  Anterior  support  rod. 

E.  Detachable  support  rod.     A  side  socket  for  E  is  shown  in  the  frame. 

F.  Nerve  electrodes. 

G.  Insulating  sleeve.     The  method   of  mounting  a  muscle-nerve  preparation  is  shown  by  the 

dotted  lines. 


weight  pan  and  other  accessories.  The  openings  in  both  ends  are  taper 
reamed  to  facilitate  attachment  of  extensions.  The  forward  arm  to 
which  the  writing  point  is  usually  affixed  is  transversely  pierced  about 
two  centimeters  from  the  end  by  a  pin  which  is  permanently  soldered 
in  place,  so  that  when  a  straw  is  forcibly  thrust  into  the  tube  it  is  split, 
and  thus  expanded  ;  or  if  the  end  be  cut  obliquely,  it  is  compressed 
firmly  between  the  pin  and  the  side  of  the  tube,  thus  providing  a  simple 
means  of  instantly  and  rigidly  affixing  straws  of  various  sizes. 


MyOGKAI'H 


The  perpendicular  arm  is  a  tube  \v1ik1i  forms  a  spring  socket  into 
which  extensions  are  thrust.     These  extensions  are  of  various  lengths; 


Fig.    3.     Myograph.      Anterio-lateral    projection. 


they  consist  of  a  brass  tube  into  one  end  of  which  a  solid  metallic  point 
is  fixed.  The  point  serves  to  attach  one  end  of  the  muscle  to  the  lever 
by  transfixing  it.  A  collar  on  the  point  serves  as  a  stop  to  the  tissue, 
and  its  lower  surface  is  at  a  known  distance  from  the  fulcrum,  usually 


Fig.  4.     Details  of  construction  of  lever,  tissue  points,  and  attachments   of  anterior  sup- 
port rod  to   frame  and   insulation. 


10 


Myograph 


three  to  five  centimeters,  depending  upon  the  length  of  the  extensions 
employed.  Backward  excursion  of  the  arm  is  limited  by  an  adjustable 
stop  or  rest  screw  which  pierces  the  posterior  wall  of  the  frame. 

A  fixed  support  for  the  other  end  of  the  muscle  is  carried  on  a 
horizontal  rod  which  is  firmly  attached  to  the  anterior  surface  of  the 
frame.  It  consists  of.  a  spring  socket  similar  to  that  of  the  perpendicu- 
lar lever  arm  into  which  are  inserted  similar  pointed  extensions.  The 
point  of  the  socket  on  the  horizontal  support  rod  is  adjustable  by  means 
of  a  set  screw  conveniently  placed,  thus  permitting  adjustment  for 
tissue  preparations  of  different  lengths.  The  extension  is  of  such 
length  that  the  lower  surface  of  the  collar,  which  acts  as  a  stop  to  the 
tissue,  is  somewhat  above  the  horizontal  plane  of  the  stop  on  the  per- 
pendicular lever  arm  extension,  so  that  the  muscle  contracts  more 
nearly  in  the  line  of  the  circumference  of  the  arc  described  by  the 
perpendicular  arm,  i.  e.,  not  tangentially.  Fig.  5.     Thus  the  movement 


Fig.   5.     Diagram  to  show  the  relation  of  the  direction   of  the  pull  of  a  muscle  to  the  arc 
of   the   perpendicular   myograph   lever. 
F.     Fulcrum. 

P.     Horizontal  plane  of  movable  point  stop. 
P'.    Horizontal   plane  of  fixed  point  stop. 
A.     Arc  of  perpendicular  lever. 
M.  and  M'.     Longitudinal  axis  of  muscle. 


of  the  lever  is  more  nearly  uniform  throughout  the  contraction.  The 
extensions  serve  not  only  as  tissue  holders  but  as  electrodes  for  direct 
stimulation  of  the  tissue.  They  may  be  easily  withdrawn  from  the 
spring  sockets  and  replaced  by  others  of  different  lengths.  The  adjust- 
able socket  for  the  fixed  arm  may  be  removed  from  the  support  rod. 
The  anterior  support  rod  is  immediately  below  and  parallel  to  the 
forward  arm  of  the  lever.     It  is  electrically  insulated  from  the  frame, 


Myockai'ii 


11 


aiul  the  forward  ciul  is  providctl  with  a  hole  for  the  i)Ur])Osc  of  making 
electrical  connection  in  order  to  lead  a  current  to  the  muscle  through 
the  fixed  muscle  point  and  electrode.  Electrical  connection  to  the  mov- 
able muscle  point  and  electrode  is  made  by  inserting  the  end  of  the 
wire  conveying  the  current  into  a  tube  provided  for  the  purpose,  Fig. 
2,  H.  No  other  form  of  binding  post  is  used,  as  they  are  more  cumber- 
some, more  prone  to  get  out  of  order,  as  through  loss  of  parts,  and 
they  are  no  more  effective  than  the  form  described.  Besides,  this 
method  of  connecting  is  time  saving. 

A  nerve  electrode  holder  for  adjustable  electrodes  is  attached  to 
the  far  side  of  the  frame,  Fig.  2,  F,  and  Fig  6.  The  body  of  the  holder 
is  of  fibre  and,  therefore,  insulates  the  electrodes  from  the  myograph 


Fig.    6.     Myograph    nerve    electrodes, 
electrical   connections. 


Details    of    construction    and    method    of    making 


frame.  The  electrodes  consist  of  brass  tubing,  into  the  lower  ends  of 
wdiich  are  fitted  metallic  points  which  are  curved  to  support  a  nerve  or 
other  tissue  laid  upon  them.  The  holes  in  the  upper  ends  of  the  tubes 
of  the  electrodes  serve  for  making  electrical  contact.  The  spring 
sockets  of  the  holder  into  which  they  fit  permit  of  their  instantaneous 
removal  or  adjustment. 

The  support  rod  attached  to  the  anterior  surface  of  the  frame  and 
which  carries  the  fixed  point  serves  in  many  experiments  as  a  support 
for  the  myograph,  as  it  may  be  clamped  to  a  stand  rod  without  inter- 
fering in  any  way  with  the  action  or  manipulation  of  the  myograph, 
Fig.  1.  In  addition,  the  posterior  and  far  sides  of  the  frame  are  pro- 
vided with  threaded  sockets  into  which  a  detachable  support  rod  may 
be  fastened  as  occasion  indicates.  The  support  rod  is  provided  with  a 
fiber  collar  so  that  it  may  be  electrically  insulated  from  the  clamp.   The 


12 


Bath 


collar  is  three  centimeters  long ;  it  is  split  longitudinally  through  one 
side  so  that  it  may  be  easily  adjusted  to  any  point  upon  the  rod  or  re- 
moved therefrom.  It  may  also  be  used  upon  the  support  rod  attached 
to  the  anterior  surface  of  the  frame.  The  support  rod  may  be  quickly 
removed  by  unscrewing  from  the  frame ;  if  tight  it  may  be  loosened  by 
using  an  ordinary  clamp  as  a  wrench.  In  addition,  it  is  pierced  trans- 
versely near  its  posterior  extremity  by  a  hole  through  which  a  pin  such 
as  a  nail  may  be  thrust  to  facilitate  its  adjustment  or  removal.  When 
the  rod  is  screwed  into  the  far  side  of  the  frame  it  is  then  fixed  at  right 
angles  to  the  direction  of  the  lever.  This  arrangement  is  very  con- 
venient as  in  recording  the  contraction  of  a  frog's  heart  in  situ. 

Various  accessory  attachments  greatly  extend  the  use  and  value  of 
the  myograph,  and,  therefore,  will  be  described  in  detail. 

Bath 

As  a  ready  and  simple  means  of  applying  solutions  to  isolated 
tissues,  the  adjustable  bath  is  used,  Fig.  7,  A,  and  Fig.  1.     The  dish 


Fig.    7.     A.  Myograph   bath   holder   and   dish. 
B.     Modified  form  of  dish  requiring  but  S  to  8  cc.  of  liquid  to  submerge  tissue. 


Bath 


13 


is  of  glass,  circular  in  form.  In  diameter  it  is  52  mm.  and  in  depth 
30  mm.  The  walls  and  bottom  are  1.5  mm.  thick.  It  is  firmly  grasped 
by  the  spring  prongs  of  the  holder,  but  is  instantly  detachable,  and, 
therefore,  is  easily  cleansed.     The  holder  is  solidly  and  substantially 


Fig.  8.     Tubular  form   of  bath  and  holder. 


A.  Holder  mounted  on  myograph  frame. 

B.  Holder  mounted  on  support  rod. 


constructed.  It  consists  of  an  open  brass  ring  attached  to  a  support 
rod  and  equipped  with  three  spring  fingers  for  holding  the  dish,  spaced 
at  equi-distant  points  of  its  circumference.  The  ring  also  acts  as  a 
spring  owing  to  the  fact  that  it  is  not  closed.     The  dish  is  firmly  held 


14 


Volume  Tube 


in  position  so  that  the  holder  may  be  inverted  without  the  dish  becom- 
ing displaced.  When  inverted,  /.  e.,  when  the  spring  prongs  are  directed 
downward,  it  serves  as  a  ring  support  for  a  beaker  in  such  experiments 
as  require  changing  the  temperature  of  the  solution. 

The  bath  renders  a  moist  chamber  unnecessary  in  most  experi- 
ments as  all  of  the  tissues  may  be  instantly  submerged  in  or  removed 
from  blood  or  salt  solutions  by  simply  raising  or  lowering  the  dish. 
The  large  surface  of  liquid  exposed  favors  gaseous  exchange  between 
the  air  and  liquid.  The  tissue  may  be  stimulated  while  submerged  in 
the  bath  or  while  exposed  to  the  air,  as  desired.  In  the  latter  case, 
undue  drying  is  prevented  by  raising  the  bath  at  intervals  to  submerge 
the  tissues. 

A  tubular  form  of  bath  and  holder  is  shown  in  Fig.  8.  The  tissue 
is  attached  to  a  fixed  point  carried  by  the  holder  and  to  the  posterior 
arm  of  the  lever.  Wire  is  used  for  attaching  the  tissue  to  the  lever. 
After  the  tissue  is  mounted  the  bath  tube  is  adjusted  from  below 
upwards  and  is  held  in  place  by  the  spring  prongs.  The  tissue  may  be 
electrically  stimulated  by  connecting  one  electrode  wire  to  the  myograph 
frame  and  the  other  to  the  bath  holder. 


Fig.    9.        Volume   tube. 


Weights  15 

The  chief  advantage  of  this  method  is  that  less  liquid  is  required 
to  submerge  the  tissue  than  in  the  regular  form  of  dish,  so  it  is  recom- 
mended only  in  experiments  where  the  quantity  of  bath  liquid  is  re- 
stricted, as  in  the  case  of  expensive  drugs.  The  modified  form  of 
ordinary  bath,  Fig.  7,  B,  requires  less  liquid  than  the  tubular  form. 
The  ordinary  form  of  dish  requires  from  about  25  to  40  cc. ;  the  modi- 
fied form  5  to  8  cc. ;  and  the  tubular  form  8  to  15  cc.  of  liquid. 

Muscle  \'olume  Tube 

A  modified  form  of  tubular  bath  shown  in  Fig.  9  serves  as  a 
muscle  volume  tube. 

Weights 

The  weights  are  flat  metallic  rectangles  measuring  about  25  by  30 
mms..  Fig.  10,  A.  A  set  consists  of  nine,  weighing  ten  grams  each, 
and  two,  weighing  five  grams  each.  Near  one  extremity  they  are 
pierced  by  a  hole  by  means  of  which  they  may  be  hung  on  a  hook  sus- 
pended from  the  lever.  Fig.  10,  B.  The  hook  is  of  such  dimensions 
and  shape  that  the  other  parts  of  the  apparatus  do  not  interfere  with 
the  placing  or  removal  of  the  weights.  Fig  11.  It  weighs  one  gram. 
At  its  point  of  contact  with  the  lever  it  is  pierced  with  a  pin  by  means 
of  which  it  is  fixed  on  any  point  on  the  lever  pierced  by  the  perpen- 
dicular holes  occurring  at  one  centimeter  intervals.  The  attachment  is 
such  that  the  hook  is  free  to  swing  with  the  up  and  down  excursions 
of  the  lever. 

Also  a  weight  pan  is  provided  for  supporting  the  weights  on  the 
lever.  Fig.  10,  C.  It  is  made  of  sheet  metal,  consisting  of  a  base  and 
two  sides.  It  is  of  such  size  that  the  weights  lie  flat  and  fit  snugly, 
but  do  not  bind.  At  one  end,  the  walls  are  bent  inward  slightly  so 
that  the  weights  cannot  pass  through.  When  adjusted  to  the  lever, 
the  narrow  end  is  away  from  the  experimenter  and  the  pan  is  tilted 
so  that  the  bottom  slopes  slightly  to  this  end.  This  is  to  avoid  dis- 
placement of  the  weights  by  the  jar  that  occurs  when  the  muscle  re- 
laxes. The  pan  is  attached  to  the  horizontal  arm  of  the  lever  by  means 
of  a  saddle  through  the  middle  of  which  a  spring  point,  slightly  longer 
than  the  diameter  of  the  horizontal  tube,  projects.  This  point  is  in- 
serted into  one  of  the  perpendicular  holes  piercing  the  lever,  and  when 
the  saddle  is  placed  in  contact  with  the  lever,  the  point,  by  virtue  of  its 
spring  quality,  binds  it  firmly  into  place.     The  pan  weighs  ten  grams. 


16 


Weights 


The  forward  arm  of  the  horizontal  lever  being  longer  than  the 
backward  arm,  the  lever  itself  serves  as  a  load  to  the  muscle.  The 
recording  extension  adds  to  this  load.  As  ordinarily  employed,  the 
load  amounts  to  two  or  three  grams,  when  the  muscle  is  attached  five 
centimeters  from  the  fulcrum.     This  being  the  case,  in  most  experi- 


Fig.    10.     Myograph  attachments. 

A.  Weights. 

B.  Weight  hook. 

C.  Weight  pan. 

D.  E,  and  F.     Special  weights. 

G.     Counterpoise  weight  showing  end-thrust  socket. 


ments,  no  additional  load  is  required.  However,  two  special  forms  of 
weights  are  sometimes  found  useful.  One  of  these  is  very  simple, 
consisting  of  a  five-gram  weight  wnth  a  saddle  and  point  arrangement 
for  attaching  it  to  the  lever.  Fig.  10,  D.  The  other  weight  is  of  a  slid- 
ing type.  Fig.  10,  E.  It  is  supported  in  part  by  a  saddle  groove  which 
rides  on  a  horizontal  lever,  but  chiefly  by  a  horizontal  arm.  Fig.  10,  F, 
carried  about  one  centimeter  above  but  parallel  with  the  horizontal 
lever  arm.  The  weight  is  attached  to  the  horizontal  arm  by  passing 
the  arm  through  a  hole  which  pierces  it.  The  arm  is  encircled  at 
centimeter  intervals  by  shallow  grooves,  and  to  one  face  of  the  weight 
is  attached  a  round  straight  spring  which  presses  into  the  grooves,  by 
means  of  which  it  is  readily  fixed  at  any  point  on  the  arm.    The  hori- 


ErGOOKAI'H — CiAS   ClIAMIiKK    I'J.IXTKODKS  17 

zontal  weight  is  attachcil  to  the  end  of  the  perpeiuHiular  arm  soL'ket 
which  pierces  the  horizontal  lever.  Connection  is  made  by  a  double 
friction  thrust  joint  which  secures  it  very  firmly  yet  permits  of  instant 
adjustment  or  removal.  Fig.  10,  G.  The  weight  is  25  grams  and 
the  weight  arm  adds  one  gram  to  the  load  of  the  lever.  The  horizontal 
arm  may  he  directed  in  auN-  horizontal  direction,  and  thus  serves  as  a 


Fig.    11.     Myograph   with  pivoted   hook  weight  support. 

counterpoise  which  may  be  desirable  when  very  delicate  tissues  are 
used.  It  is  particularly  useful  when  the  lever  is  used  for  recording 
the  contractions  of  the  hearts  of  small  frogs,  as  by  simply  rotating  it, 
the  load  is  instantly  and  delicately  adjusted. 

Ergograph 

The  ergograph  attachments  consist  of  a  coil  spring,  pulley,  cord, 
and  finger  loop  and  cord  holder  for  attaching  to  the  myograph.  Fig.  12. 
An  L  rod  serves  as  the  hand  holder.  The  apparatus  is  assembled  as 
shown  in  the  figure.  It  is  very  easily  adjusted  through  a  wide  range 
for  tension,  etc. 

Gas  Chambi^r  Electrodes 

This  electrode  accessory  is  designed  for  studying  the  efifect  of 
gases  and  volatile  substances  upon  the  irritability  and  conductivity  of 
nerve.  It  consists  of  a  short  cylinder  of  hard  rubber  containing  a 
longitudinal  cavity.  Fig.  13.  It  is  supported  on  a  tube.  The  tube  com- 
municates wath  the  cavity  and  further  serves  for  the  introduction  of 
gas.  The  wall  of  the  chamber  is  transversely  slit  at  right  angles  to  the 
support  from  above  downward,  through  about  four-fifths  of  its  extent, 
which  provides  a  means  for  extending  the  nerve  across  the  cavity.  The 
top  of  the  cavity  and  the  greater  part  of  the  transverse  slit  are  closed 


18 


Gas  Chambkr  Electrodes 


by  a  metal  cap  bearing  a  wide  flange  to  hold  it  in  place.  The  electrode 
points  are  placed  horizontally  in  the  cavity  at  a  level  slightly  higher 
than  the  bottom  of  the  transverse  groove.  The  points  are  set  at  right 
angles  to  the  holders  which,  therefore,  are  perpendicular.  The  holders 
are  set  firmly  in  the  rubber,  and  their  upper  free  ends  serve  to  connect 
the  wires  from  the  coil  or  battery. 


Fig.  12.     Myograph  with  ergograph  attachments. 


The  dimensions  are  such  that  the  electrode  may  be  adjusted  to 
the  nerve  between  the  point  of  contact  of  the  nerve  on  the  myograph 
nerve  electrode  and  the  entrance  of  the  nerve  into  the  muscle  without 
removing  the  bath  from  the  preparation.  It  may  be  lowered  so  that 
the  nerve  is  submerged  in  the  bath.  This  is  an  advantage  in  long 
experiments  in  preventing  undue  drying,  and  also  in  removing  any 
substance  to  which  the  nerve  may  have  been  exposed.  During  the  time 
of  passage  of  the  gas,  the  electrode  is  raised  until  the  bottom  is  free 
of  the  surface  of  the  bath  solution. 


Gas  Chambkk  Ei.ixtrodes 


19 


Usually  observations  upon  both  excitability  and  conductivity  are 
made,  Fig.  14.  The  stimulating  current  is  switched  at  will  from  the 
gas  chamber  electrode  to  the  myograph  nerve  electrode  by  means  of 
the  combined  primary  and  secondary  key,  Fig.  38. 


Fig.    13.     Gas   chamber   electrodes. 


Among  the  advantages  of  this  form  of  gas  electrodes  is  the  ease 
and  rapidity  Avith  which  the  nerve  may  be  attached  or  disconnected 
from  it  without  injury. 


Fig.  14.     Effect  of  ether  vapor  on  conductivity  and  excitability  of  nerve. 

A.  Vapor  applied. 

B.  Vapor  removed. 

C.  Response  to  stimulation  of  nerve  central  to  gas  chamber. 
E.  Response  to  stimulation  of  nerve  in  gas  chamber. 


The  gas  is  passed  into  the  support  tube  and  thus  into  the  chamber, 
by  a  rubber  tube  slipped  over  its  outer  end,  the  other  end  being  con- 


20 


Thermal  Ei.Kctrodes 


nected  with  the  generator  or  source  of  supply.  For  chloroform,  ether, 
alcohol,  ammonia,  and  the  like,  i.  ^./volatile  liquids  or  solutions  of 
gases,  the  substance  is  placed  in  a  small  glass  bottle  or  other  suitable 
container,  and,  if  necessary,  volatilization  is  accelerated  by  placing  the 
container  in  a  vessel  of  water,  the  temperature  of  which  can  be  varied. 


Fig.    IS.        Generator. 

For  studying  the  effect  of  gases,  as  carbon  dioxide,  a  compact  form  of 
generator  is  provided,  the  parts  of  which  are  substantially  mounted  on 
a  base  for  convenience  in  handling  and  storing.  Fig.  15. 

Thermai,  EIvECTRODES 


The  thermal  electrodes  consist  of  a  brass  box  which  is  closed 
excepting  for  an  inflow  and  outflow  tube  mounted  on  the  back.  Fig.  16. 
The  outflow  tube  is  left  sufficiently  long  to  serve  also  as  a  support  by 
attaching  it  to  a  clamp.    Temperature  change  is  effected  by  circulating 


T  u  i:i<  M  A  I.  Im.kctkodks 


21 


vvann  or  cold  solutions  throujjh  the  cavity  by  means  of  rubber  tubes 
attached  to  the  inrtow  and  outflow  tubes  and  to  a  reservoir,  and  a 
vessel  for  receivinsj^  the  outflow. 

A  brass  tul)e  is  soldered  to  one  side  of  the  box.  The  lower  end  is 
closed.  Salt  solution  is  ])laced  in  the  tube  and  into  this  the  bulb  of  a 
thennonieter  is  inserted.  It  adequately  holds  and  supi)orts  the  ther- 
nioiueter  since  its  position  is  perpendicular,  and  in  diameter  it  is  onlv 


Fig.    16.     Thermal   electrodes 


slightly  larger  than  the  thermometer  bulb.  The  salt  solution  placed 
in  the  tube  forms  a  thin  layer  around  the  walls  owing  to  its  displace- 
ment by  the  thermometer  and  therefore  its  temperature  quickly  follows 
any  change  in  temperature  of  the  metal.  And  since  the  temperature 
of  the  metal  closely  follows  the  temperature  of  the  solution  circulating 
in  the  box,  the  thermometer  indicates  very  nearly  the  temperature  of 
the  apparatus.  The  bottom  of  the  box  extends  outward  for  a  short 
distance  beyond  the  front  surface  and  then  bends  upward  at  a  right 
angle  and  terminates  at  a  distance  of  about  one  centimeter  from  the 
bottom.  Thus,  a  broad  slit  bounded  on  three  sides  by  metallic  surfaces 
is  formed  at  the  lower  margin  of  the  front  of  the  box.  A  pair  of 
electrodes  is  fastened  to  the  upper  part  of  the  front  of  the  box,  from 
which  they  are  insulated,  and  extend  downward.  The  points  are  in- 
sulated from  the  front  of  the  box  adequately  to  prevent  shortcircuiting. 
Near  the  points  and  near  the  bottom  of  the  groove  through  which  they 


22  Cardiograph 

extend  they  are  bent  forward  at  right  angles  and  are  firmly  attached 
by  non-conducting  material  in  holes  in  the  perpendicular  portion  of 
the   lip. 

In  use,  the  nerve  is  carried  downward  into  the  slot  until  it  rests 
upon  the  electrodes.  The  slot  is  then  filled  with  salt  solution,  the  greater 
part  of  which  it  retains  through  capillarity.  Thus  that  portion  of  the 
nerve  resting  upon  the  electrodes  is  surrounded  by  salt  solution,  the 
temperature  of  which  must  closely  follow  temperature  changes  as  indi- 
cated by  the  thermometer,  for  relative  to  its  mass,  a  large  area  of  the 
surface  of  the  salt  solution  is  in  direct  contact  with  the  metal  of  the 
box  and  lip. 

The  design  and  dimensions  of  the  thermal  electrode  are  such  that 
it  may  be  readily  adjusted  to  the  nerve  without  removing  the  nerve 
from  the  myograph  electrode  or  lowering  the  bath.  When  it  is  desired 
to  produce  a  change  in  temperature,  the  thermal  electrode  is  raised 
until  it  is  free  of  the  surface  of  the  bath  solution ;  or  the  same  end  is 
accomplished  by  lowering  the  bath. 

To  lower  or  raise  the  temperature,  cold  or  hot  brine  is  circulated 
through  the  cooling  chamber. 

This  form  of  thermal  electrode  presents  a  ready  means  of  studying 
the  effect  of  temperature  and  with  the  expenditure  of  but  little  time. 
In  addition,  the  temperature  is  under  adequate  control  and  wdde  fluctua- 
tions can  be  produced  at  will. 

Cardiograph 

Isolated  heart  muscle  is  studied  by  attaching  it  to  the  fixed  and 
movable  points  of  the  myograph.  The  base  of  the  auricles  is  trans- 
fixed on  the  stationary  point,  and  the  apex  of  the  ventricle  on  the 
movable  point.  Or  the  heart  may  be  transfixed  at  the  auricular- 
ventricular  junction  by  the  fixed  point  and  either  the  apex  of  the 
ventricle  or  the  base  of  the  auricle  transfixed  by  the  movable  point. 
Or  the  auricles  and  ventricles  may  be  separately  attached  to  the  points. 
Tracings  taken  by  this  method  are  shown  in  Fig.  17,  B  and  C.  In  the 
same  way  strips  of  heart  tissue  are  attached  to  the  points  and  studied. 

The  heart  may  be  studied  in  situ  in  much  the  same  way.  After 
removing  the  anterior  wall  of  the  chest,  the  animal  is  brought  upward 
in  such  a  position  that  the  points  transfix  the  heart.  By  using  longer 
points  the  lever  may  be  adjusted  to  the  heart  of  a  cat  or  dog.     Two 


CAKPKlOKAril 


23 


levers  may  be  attached  to  one  heart  and  both  auricular  and  ventricular 
contractions  separately  and  coincidently  recorded. 

The  lever  is  also  adapted  to  studying  the  heart  in  situ  by  the  sus- 
pension method.  See  tracing,  Fig.  17,  A.  For  this  purpose  the  points 
and  electrodes  may  be  removed.    The  posterior  support  rod  is  removed 


Fig.    17.     Heart  tracings   from   a   31.5   gm.   frog. 

A.  By  suspension  method  with  regular  myograph. 

B.  Heart  isolated  and  auricles  and  ventricle  attached   to  points  of   myograph. 

C.  Ventricle   only   attached  to  points   of   myograph. 


and  attached  to  the  far  side  of  the  frame.  Or  it  may  be  removed  and 
the  lever  held  by  clamping  the  anterior  support  rod.  The  animal  is 
placed  beneath  the  lever  and  a  thread  attached  to  the  apex  of  the 
ventricle  or  auricles  is  carried  upward  and  fastened  about  the  posterior 
(horizontal)  arm  of  the  lever.  A  holder  is  provided  for  fastening  the 
thread.  By  thus  employing  two  levers  at  the  same  time,  both  auricular 
and  ventricular  contractions  may  be  recorded.  This  method  is  especi- 
ally useful  for  turtles. 


24 


Cardiograph 


For  studying  the  frog's  heart  in  situ,  a  pad  and  support  method  is 
convenient  and  effective,  Fig.  18.  The  heart  is  supported  on  a  metalhc 
finger  or  spoon  rest  which  is  connected  through  an  insulation  block  to 
the  frame  above  by  means  of  a  screw  passed  through  the  posterior 
su])port  rod  socket.  The  pad  consists  of  a  small  disk  of  cork  (which 
may  be  cut  from  the  end  of  a  stopper)  attached  to  the  movable  point 


Fig.    IS.     Myograph  arranged  for  studying  frog's   heart   in  situ. 

A.  Insulated  heart  support.    Note  tubular  socket  on  side  of  strip  for  the  electrode  connection. 

B.  Cork  pad   on  tissue  point  for  transmitting  niov€ment   of   heart. 

C.  Counterpoise  weight. 


by  transfixing  it  near  the  center.  The  point  emerges  from  the  lower 
surface  of  the  disk  so  that  it  slightly  penetrates  the  tissue  and  thus 
serves  to  prevent  horizontal  movement  between  the  pad  and  the  heart. 
The  frog  is  supported  on  a  board  clamped  to  the  stand  support  rod 
below  the  lever,  Fig.  19.  By  a  slight  movement  of  either  the  lever  or 
frog  board  the  heart  may  be  instantly  adjusted  to  or  removed  from 
the  lever. 

In  all  the  above  experiments  where  delicacy  of  poise  of  the  lever 
is  an  essential  requirement,  this  may  be  instantly  carried  out  by  means 
of  the  right  angle  weight  support  bar,  or  sj^ecial  right  angle  counter- 
poise provided  for  the  purpose,  Fig.  10,  G.  Attachment  between  the 
weight  and  the  lever  is  made  by  means  of  a  double  end -thrust  contact 
between  the  socket  on  the  weight  and  the  tubular  cup  provided  on  the 
top  surface  of  the  lever  on  a  perpendicular  line  through  the  fulcrum. 


Hl.IX'TRODKS 


25 


It   is  easy  to  ol)tain  the   desired  adjustment   of  load  by  rotating  tlie 
weight  horizontally. 

To  stimulate  the  heart  directly,  in  the  pad  and  rest  method  of 
attachment,  an  electrical  contact  tube  is  provided  on  the  metal  portion 
of  the  rest,  and  for  the  other  contact  the  tube  on  the  frame  is  employed. 
Thus  an  electrical  current  may  be  transmitted  between  the  movable 
point  and  the  rest  through  the  heart  tissue  placed  between  them. 


Fig.   19.     Myograph  arranged  as   frog  cardiograph  and  mounted   with   frog   board   and   de- 
tachable electrodes.     Insert  shows  adjustment  to  frog. 

Simple  Electrodes 


A  pair  of  adjustable,  detachable  electrodes  is  shown  in  Fig.  20. 
The  electrodes  consist  of  a  support  rod  attached  to  a  fibre  block  into 
which  the  electrode  point  holders  are  fixed.    The  points  are  sufficiently 


25  Special  Cardiograph 

long  to  render  adjustment  easy.  Near  their  free  extremities  they  are 
bent  outward  at  an  angle  to  provide  a  rest  for  the  nerve.  Electrical 
connection  is  made  by  inserting  wires  into  the  top  ends  of  the  holders. 
In  the  experiments  on  the  frog  as  just  described,  the  electrodes  are 
supported  on  an  L  rod,  which  in  turn  is  clamped  to  the  stand  support 
rod  sleeve  below  the  clamp  wdiich  holds  the  frog  board.  Thus  it  is 
possible  to  adjust  the  electrodes  quickly  in  any  position  desired,  and 
since  they  are  rigidly  supported  they  maintain  a  very  constant  adjust- 
ment to  the  nerve. 


Fig.   20.     Adjustable  electrodes. 
B.     Adjustable   electrodes    with    electrical    contact   surfaces    in    posterior    end    of    support    rod. 
An  insulating  collar  similar  to  the  one  shown  in  Fig.   2,   G,  is  provided. 

This  electrode  is  convenient  for  use  on  frogs  and  turtles,  and  in 
certain  experiments  on  mammals.  It  may  be  used  for  stimulating 
muscle  directly,  as  in  the  case  of  the  turtle's  heart,  by  lightly  placing 
the  lower  surfaces  of  the  bent  ends  against  the  muscle,  in  which  posi- 
tion it  may  be  held  by  a  clamp  attached  to  a  support. 

SpEciaIv  Cardiograph 

A  special  form  of  heart  lever  has  been  designed  for  studying  the 
heart  by  the  suspension  or  the  pad  and  rest  method.  Fig.  21.  It  is 
employed  precisely  as  has  been  described  for  the  regular  lever  and 
presents  no  points  of  superiority  other  than  those  conferred  by  the  fact 
that  being  designed  especially,  it  is  somewhat  smaller,  particularly  due 
to  cutting  down  of  the  frame,  and  to  the  absence  of  frame  accessories. 
The  movable  point  is  not  attached  at  the  fulcrum,  but  one  or  two  centi- 


Frog  Holder 


27 


meters  in  front  of  it.  Its  chief  advantage  lies  in  the  fact  that,  due  to 
cutting  down  of  the  frame,  in  the  pad  and  rest  method  a  shorter  mov- 
able point  can  be  employed  and  thus  a  greater  magnification  secured. 


Fig.   21.     A.   Special   cardiograph. 
Tracing  taken  with  above  form  of  cardiograph. 

S.   Sinus.     A.  Auricles.     V.  Ventricle.     B.  Bulbus. 


Frog  Holder — Form  I 


The  frog  holder  consists  of  a  wooden  base  topped  with  a  thick 
pressed  cork  pad,  the  two  being  firmly  united  by  cement  and  brass 
brads.  Fig.  22.  The  dimensions  are  150  x  100  x  10  mm.  To  one  side 
50  mm.  from  one  end  a  support  rod  is  attached  at  right  angles  to  the 
long  dimension  by  means  of  screws  inserted  into  holes  in  the  broadened 
end  of  the  rod  and  turned  into  the  bottom  of  the  board.  This  serves 
to  support  the  board  on  the  stand  support  rod  by  means  of  a  clamp. 


Form  II 

The  adjustable  form  of  holder  shown  in  Fig.  23  is  convenient  for 
certain  experiments  as  it  permits  of  a  wide  range  of  adjustment.  A 
threaded  socket  provides  for  the  direct  attaching  of  a  support  rod  for 


28 


Frog  Holder 


mounting  electrodes  and  a  hole  near  the   forward  outer  corner   for 
microscopical  observation  of  circulation  in  membranes. 

Frogs  are  fastened  to  the  holder  by  means  of  pins,  as  the  method 
is  simple,  rapid,  efficient — and  pins  are  easily  obtained  to  replace  those 
lost.  The  holder  when  assembled  is  water-proofed  by  soaking  in  hot 
paraffine,  so  it  is  easily  cleansed  by  wiping  with  a  moist  cloth  or  sponge 


Fig.    22.     Frog   holder.      Form    I. 

or  washing  in  cold  water.  Obviously,  hot  water  should  not  be  applied 
to  it.  It  is  sufficiently  large  for  ordinary  frogs,  and  not  being  cumber- 
some, takes  up  but  little  room.  It  is  readily  adjustable  to  any  position 
desired  and  being  designed  especially  for  use  with  the  myograph,  it 
meets  all  ordinary  requirements.     (  See  Figs.  23a  and  23b.) 

Form  III 


This  form  of  holder,  Fig,  24.  is  particularly  useful  for  graphically 
recording  results  in  reflex  experiments,  character  and  site  of  action  of 
drugs  with  the  circulation  intact,  etc.  (cf.  Am.  Jr.  Phys.,  1910,  xxvi, 
329).  Owing  to  the  ease  with  which  accurate  and  stable  adjustments 
can  be  made,  and  the  absolute  control  of  the  current,  very  accurate 
results  are  obtained. 


I'koG    lllll.DKR 


29 


'iMic  wootlen  base  is  screwed  to  an  iron  shelf  l)racket,  which  is 
jirovidcd  with  a  socket  and  set  screw  for  attaching  to  a  stand  rod. 
The  floor  of  the  base  is  covered  with  a  cork  j)ad  which  is  boiled  in 
paraftine  and  laid  while  the  paraffine  is  melted  and  pressed  until  the 
parafitine  sets.     The  anterior  third  of  the  floor  has  a  double  thickness 


\!\ 


"^ 


^ 


Fig.   li.     Adjustable   frog  holder.      Form   II. 
A.      Side   view.  B.      Bottom   view. 

1.  Adjustable   support   rod. 

2.  Electrode  support   rod  socket. 

3.  Hole  for  microscopical  examination   of   frog's  web. 


of  cork,  the  posterior  edge  of  which  is  beveled.  Owing  to  the  treat- 
ment with  paraffine,  the  floor  is  water-proof,  and,  therefore,  is  easily 
kept  clean.  And  being  of  cork,  pins  may  be  readily  thrust  into  it  to 
hold  the  frog. 

Three  pairs  of  electrode  holders  w-ith  adjustable  electrodes  are 
mounted  along  either  side.  The  holders  are  so  spaced  that  the  gastroc- 
nemius muscle,  sciatic  nerve,  and  fore  limb  skin  or  nerves  may  be 
stimulated.  Or  all  three  pairs  may  be  adjusted  to  the  sciatic,  as  in 
studying  the  local  action  of  reagents  on  the  nerve  trunk.  A  tubular 
metal  container  is  provided  for  the  electrodes  when  not  in  use.  A 
special  multiple  key  and  switch   serve  to  control  the  current  to  the 


30 


Turtle  Holder 


electrodes.  The  construction  of  the  key  is  the  same  as  in  the  combined 
primary  and  secondary  cut-out  key,  switch  and  commutator,  Fig.  38. 
No  unipokir  stimulation  can  occur. 


Fig.  23a.  Frog  holder  assembled  with  special  duplex  myograph  clamp  and  two  myographs 
and  two  pairs  of  electrodes  for  simultaneous  tracings  from  both  gastrocnemius  muscles  in  situ. 
The  tendons  of  the  muscles  are  connected  directly  to  the  levers  by  the  tissue  points. 


Turtle  Hoi.der 

The  holder,  which  is  of  wood,  consists  of  a  base  measuring 
200x200x25  mm.,  and  two  rests  measuring  45  x  45  x  150  mm.  The 
rests  are  attached  to  opposite  sides  of  the  base  so  that  their  facing 
surfaces  are  parallel  and  about  110  mm.  apart.  Fig.  25. 

The  central  portions  of  the  upper  inner  corners  are  concave  for 
a  distance  of  110  mm.  and  a  depth  of  10  mm.  in  the  middle.  The  base 
and  rests  are  finished  with  a  water-proof  paint  or  varnish. 

Two  metal  pins  are  set  obliquely  in  one  end  of  the  base  for  attach- 
ing the  head.     A  nickeled  support  rod  10  cms.  long  rising  from  the 


Tuning  Fork 


31 


forward  end  of  one  of  the  rests  provides  a  means  of  attaching  elec- 
trodes, etc. 

A  terrapin  or  tnrtle  is  mounted  by  placing  it  back  down  upon  the 
holder.  It  is  lield  in  place  by  pressing  with  one  hand  upon  the  ventral 
plate.  A  short  hook  formed  on  one  end  of  a  steel  rod,  Fig.  25,  D.  is 
then  pressed  under  the  "chin"  and  ihc  head  withdrawn   and  crushed 


^1            /      1/ 

rf 

1           *    jjA^kt.        1 

M^^                1                 1 

-^^ 

Fig.  23b.  Side  view  of  assemblage  to  illustrate  the  method  of  supporting  the  frog  board 
and  electrodes  by  means  of  L  rods.  The  board  clamp  is  not  shown.  All  clamps  on  the 
main  support  rod  should  be  atttached  to  a  sleeve  for  convenience  of  perpendicular  adjust- 
ment to  the  drum.  The  tendons  of  the  muscles  are  connected  to  the  myographs  by  means 
of  threads  and  special  extensions  attached  to  the  levers.  The  electrodes  are  adjusted  to 
the  sciatic  nerves.     (For  sleeve,  see  Fig.   1  or  16.) 


with  gas  pliers.  A  piece  of  wire  is  then  bound  tightly  about  the  upper 
part  of  the  neck  to  prevent  hemorrhage  and  the  pliers  removed  and 
the  neck  placed  between  the  bars  of  the  holder  and  fastened  by  means 
of  the  ends  of  the  wire.  The  feet  are  then  fastened  to  the  ends  of 
the  rest  block  with  nails.  Roofing  nails,  which  are  short,  thick,  and 
sharp-pointed,  are  convenient  for  this  purpose.  The  ventral  plate  is 
then  removed  with  a  hack  saw  and  knife  and  any  bleeding  vessels 
ligated.  when  the  preparation  is  ready  for  use. 

Tuning  Fork 

The  tuning  fork  made  by  the  Harvard  Apparatus  Company  is 
modified  to  the  extent  of  slittinsf  one  of  the  ends  near  one  side  to 


32 


TuxiNG  Fork 


facilitate  attachment  of  a  writing  point.  Fig.  26.  ]\lade  of  good  quality 
of  paper  or  of  thin  celkiloid  and  fastened  with  seahng  wax,  the  writing 
points  give  excellent  results  and  rarely  need  adjustment. 

For  starting  the  fork  to  vibrate,  a  block  of  hard  wood,  measuring 
28  x22  X  23  mm.  and  e(|uipped  on  one  side  with  two  brass  pins  4  mm. 
in  diameter  screwed  lirmly  into  the  block,  is  used.     The  pins  are  set 


Fig.  24.  Compound  frog  holder,  Form  III,  and  key.  The  frog  holder  is  e(iuipped  with 
two  special  myographs,  but  the  regular  form  can  be  used.  The  six  pairs  of  binding  posts 
mounted  on  the  holder  serve  as  electrode  holders.  An  electrode  is  shown  in  the  right  of  the 
figure.  The  cylindrical  case  attached  to  the  side  of  the  holder  is  a  container  for  the  electrodes 
when   not  in  use. 

On  the  key  the  binding  posts  marked  P  and  P'  are  connected  in  the  primary  circuit,  and 
S  and  S'  in  the  secondary  circuit  of  an  induction  coil.  The  battery  current  may  be  lead  to 
the  tissues  by  connecting  to  the  posts  S  and   S'. 


13  mm.  apart.  They  project  7  mm.  from  the  surface  of  the  block,  and 
their  facing  sides  are  filed  in  a  sloping  manner  so  that  their  nearest 
point  of  approach  is  near  their  free  ends.  The  appliance  is  attached 
to  the  fork  by  springing  the  bars  together  with  one  hand  and  sliding 
the  projecting  pins  on  the  block  over  their  outer  surfaces  from  their 
free  ends  backward.  Owing  to  the  sloping  surfaces  of  the  pins  they 
bind  on  the  fork  near  their  points  only,  and,  therefore,  they  firmly 
hold  to  the  bars  after  the  hand  is  removed.    To  set  the  fork  vibrating, 


Tlning  Fork 


33 


the  block  is  riMiiovcd  by  a  tuniin.L;  niovcinriit  from  hcfore  l)ack\var(l. 
'I'he  backward  ods^o  of  the  face  in  contact  with  the  e<l.sj;es  of  the  l)ars 
is  used  as  a  fulcrum,  and  the  points  of  the  pins  are  forced  to  slide  from 
the  bars  without  jar  or  misplacement  of  the  instrument  as  a  whole. 


Fig.   25.     Turtle   holder. 


A.  and  A'.      Rests. 

B.  Head  holder. 

C.  Support   rod. 

D.  Hook  for  withdrawing  head. 


o 
o 

Fig.  26.     Tuning  fork  and  starter. 

A.  Slot  in   fork  for  writing  point. 

B.  Metliod   of   using   starter. 

C.  Details  of  construction  of  starter. 


34 


SiGXAL 

Signal — Form  I 


The  electro-magnet  signal  is  of  compact  form,  Fig.  27.  It  meas- 
ures in  greatest  diameter  8  mm.  and  in  extreme  length  112  mm.  An 
extension  holder  is  provided  by  means  of  which  the  length  may  be 


ScolLc      \y»     ctw- 


o 


s 


I — < 


s 


\-^-oi 


o       -f^ 


7L 


I 1 


B 


Scale    \n   ctcv  .  ^ 

Fig.   27.        Electro-magnet   signal. 

A.  External  view  of  signal. 

B.  Side  view,  cover  removed,   showing  the  magnet  and  the  vibrator. 

C.  Cross-section. 

D.  Extension  holder. 

E.  Extension   holder  attached.      (See   Fig.    68    for   tracing.) 


7i] 


SiGNAI, 


35 


increased  150  nini..  which  is  adequate  for  all  purposes.  The  magnet 
is  placed  horizontally  and  is  enclosed.  The  vibrator  is  of  the  spring 
type  and  is  mounted  j)arallel  with  the  magnet  and  is  enclosed,  excepting 
its  outer  end.  which  receives  the  recording  point.  The  ])oint  is  pro- 
tectetl  by  a  guard.  When  not  in  use.  the  cover  sleeve  may  be  partially 
withdrawn  from  the  magnet  base  and  thus  it  serves  to  guard  the  re- 
cortling  ])oint  from  accidental  injury.  Electrical  connection  is  made  by 
inserting  the  ends  of  wires  into  sockets  provided  on  the  posterior  end 
of  the  rod. 

The  resistance  of  the  signal  is  about  0.5  ohm.  It  works  efficiently 
connected  in  series  with  a  Porter  coil  and  one  ordinary  dry  cell.  It 
has  considerable  lag,  but  it  will  vibrate  efficiently  a  hundred  times  or 
more  per  second.  It  has  some  secondary  vibration,  but  for  all  ordinary 
drum  speeds  this  does  not  introduce  a  practical  disadvantage.  See 
Figs.  52,  and  68,  C  and  D. 

Form  II 

This  signal  has  about  0.0025  second  lag.  It  has  very  little  sec- 
ondary vibration.  It  is  constructed  with  a  pivot  angle  magnet  bar  and 
point  holder  controlled  by  a  spring,  Fig.  28.     In  this  form  the  magnet 


Fig.    28.      Signal   magnet   with    rigiit   angle   form    of   vibrator. 

A.  External  view. 

B.  Cross-section.      1.   Right   angle    vibrator.      2.   Vibrator    spring. 

C.  Signal  recording  on  slow  drum. 

D.  On   fast  drum.     Lower  tracing  is  tuning  fork  at   100  DV  per  second. 


cover  is  square  and  measures  9.5  x  35  mm.  The  support  arm  is  round 
and  measures  6.5  x  80  mm.  As  in  the  other  form,  an  extension  is 
provided.  The  magnet  is  mounted  as  in  the  other  form  of  signal  and 
the  resistance  and  method  of  making  electrical  connections  are  the 
same.     See  also  Fig.  68,  A  and  B. 


36 


Drum  Key 
Drum  Key — Form   I 


This  key,  Fig.  29,  consists  essentially  of  a  fixed  and  an  adjustable 
contact  point,  A  and  B,  in  connection  with  the  binding  post,  P,  between 
which  a  movable  arm,  C,  in  connection  with  another  binding  post,  P', 
is  placed  in  such  a  manner  that  when  it  is  swung  through  part  of  an 
arc  its  contact  surface  engages  successively  with  the  contact  surfaces 
of  A  and  B,  thus  opening  or  closing  the  primary  circuit.  The  key  is 
used  by  clamping  it  to  a  stand  in  such  a  position  that  the  free  end  of 


-Scctle     Lu    cm.. 


Fig.  29.     Drum  key,   Form   I.     It  is  connected   in  the  primary  circuit  and   a  .stop   on  the 
drum  acting  upon  the  swinging  bar  C  opens  the  contact  with  A   and   B.      (cf.    Fig.    1.) 


the  swinging  arm,  C,  is  acted  upon  by  a  suitable  catch  adjusted  to  a 
drum  for  that  purpose  (cf.  Figs.  1  and  59).  The  key  may  be  used  for 
throwing  in  a  single  break  shock ;  or  by  adjusting  it  so  that  the  swinging 
arm  engages  with  both  contact  points  two  successive  stimuli  may  be 
thrown  in,  the  interval  between  the  stimuli  depending  upon  the  distance 
between  the  two  contact  points  of  the  arms  A  and  B  and  upon  the  rate 
of  the  drum.  Closing  currents  from  the  secondary  coil  are  reduced 
to  sub-threshold  magnitude  by  separating  the  primary  and  secondary 
coils.  Though  such  interpolated  sub-threshold  stimuli  introduce  no 
practical  difficulties,  the  key  is  not  perfect.  But  it  is  practical  and  satis- 
factorv  for  ordinarv  student  use. 


W)  Kz:) — !^ 


37 


Fig.  30.      Drum  key,  Form  II. 
P,  P.     Battery  posts.         P',  P'.     Rhtocord  posts. 

A.  Swinging  contact  arm.     It  engages  with  the  bars   B,   C,  and   D. 

B.  Bar    for    contact   without    rheocord.      It    connects    with    circuit    only    through    L,'    and 

swinging  contact  arm. 

C.  Bar    for   contact    with    rheocord.      It    connects    with    circuit    through    L"   and    swinging 

contact    arm.      Also,    contact    may    be    made    with    the    bar    D    by    means    of    the 
screw   S. 

D.  Bar  for  breaking  circuit   or  reducing  current.      The   time   of  circuit   breaking  is   con- 

trolled by  the  calibrated   screw   S'. 

E.  Insulation. 

F.  Socket   for   attaching   the   key   to   its   support    on   the   drum   base.      The   cross   bar   fits 

into  a  slot  in  the  support  and  the  set  screw  binds  it  rigidly  in  place. 
(Tracings  taken  with  this  key  are  shown  in  Figs.  33  and  34.) 


38 


Drum  Key 
Form  II 


The  form  of  key  shown  in  Fig.  30  is  more  nearly  perfect  both 
practically  and  theoretically,  but  it  is  somewhat  more  complicated. 
In  this  key  the  current  is  suddenly  reduced  from  maximum  to  50  per 
cent  (or  less),  which  causes  the  first  shock,  and  from  50  per  cent  (or 


(I  '  \ 


Fig.    31.     Diagram    of    key,    Form    II. 

A.  Diagram   showing  circuits  through  key. 

B.  Diagram   to   show   wiring  with   other  apparatus. 


Cu.Tr-e»^t 
Un'iti. 

too 


SO 

0 

K-ej  ,    3o 


1  * 

B 


Fig.   32.     Diagram  of  primary  circuit  change  with  the  two  forms  of  drum  keys  described. 

1.  When  used   for  one  stimulus. 

2.  When  used  for  two  stimuli. 

less)  to  zero  for  the  second  shock.  Fig.  32.  The  continuous  sliding 
contacts  are  very  efficient  and  all  adjustments  are  simple  and  easily 
made.  The  resistance  is  adjusted  with  a  rheocord,  Figs.  31  and  35. 
In  a  special  form  of  the  key  a  rheocord  may  be  mounted  in  the  base. 


RhE0C(ikii  and  Ukiiick  39 

The  contact  bars  arc  str()ii<;Iy  mounted  and  insulated.  Contact  is 
controlled  hy  a  screw  haviufj  a  lar<j^e  calibrated  head.  The  key  may  Ijc 
instantly  adjusted  for  single  shocks  or  two  shocks  separated  by  varying 
intervals.  The  interval  between  the  shocks  may  be  made  very  slight. 
Figs.  33  and  34  are  tracings  obtained  with  this  key. 


Fig  3.^.     This  tracing   (summation  of  stimuli)    indicates  the   accuracy   of  the  key   and   con- 
stancy of  the  drum  speed  as  five  tracings  were  superposed  with  both  one  and  two  stimuli. 

COMBINKD   RhKOCORD   AND   BrIDGE 

Form  I 

The  instrument  is  of  compact  form,  Fig.  35.  The  base  is  square 
and  measures  90  x  90  mm.  The  total  height  is  about  90  mm.  It  is  of 
rotating  type.  The  resistance  is  Mangan  wire.  It  is  wrapped  in  spiral 
grooves  turned  in  a  hard  rubber  hollow  core.  There  are  30  turns  of 
wire.  The  total  resistance  is  6  ohms.  The  lower  end  of  the  wire  is 
attached  to  a  binding  post,  which  is  designated  zero.  The  upper  end  is 
carried  to  the  base  through  a  thick  copper  connection  and  connects 
with  a  post  designated  100.  The  sliding  contact  is  of  spring  brass  and 
is  attached  to  the  inside  of  the  cap,  Fig.  36.  The  cap  rotates  upon  a 
threaded  rod  which  is  solidly  attached  in  the  center  of  the  inside  of 
the  top.  The  threads  of  the  rod  engage  with  the  threads  of  a  brass 
socket  attached  to  the  upper  end  of  the  rubber  core.  The  thread  of  the 
rod  and  socket  is  of  the  same  dimension  as  the  thread  of  the  rubber 
core  into  which  the  resistance  wire  is  wound.  Therefore,  when  the 
cap  is  rotated  the  slider  very  accurately  follows  the  resistance  wire. 
A  thick  brass  connection  unites  the  threaded  socket  with  a  post  on  the 
base  designated  S.  The  upper  rim  of  the  cap  is  milled  to  facilitate 
rotation.     Around  the  lower  margin  the  cap  is  calibrated  in  20  equal 


40 


Rheocord  and  Bridge 


divisions.  A  post  is  mounted  on  the  base  perpendicularly  so  that  it 
extends  upward  closely  along  side  of  the  cap.  It  carries  30  transverse 
calibrations,  which  are  spaced  according  to  the  distance  between  the 

turns  of  resistance  wire.     The  calibrations  are  numbered  from  below 


Fig.  34.  Summation  of  stimuli  by  muscle  and  refractory  period.  The  interval  between 
the  stimuli  was  progressively  shortened  so  that  finally  (D)  the  second  stimulus  fell  within 
the  refractory  period.     Key  II.  employed. 

upward  by  fives  from  0  to  30.  Readings  are  taken  from  the  lower 
edge  of  the  cap  and  indicate  directly  the  number  of  turns  of  resistance 
wire  between  zero  and  the  slider,  while  the  calibrations  around  the 
lower  end  of  the  cap  are  read  off  against  the  edge 'of  the  post  and 
indicate  the  fractions  of  turns  of  wire.     The  readings  indicate  directly 


RnKdCOKIl    AND    UkIIICK 


41 


the  actual  resistance.  Since  the  30  turns  of  wire  have  a  resistance  of 
6  ohms,  each  turn  has  a  resistance  of  .20  ohms,  and  as  there  are  20 
divisions  on  the  cap  each  chvision  on  the  cap  represents  .01  ohm.     For 


Fig.   35.      Combined   rheocord  and   bridge,   Form   I. 

A.  Top  view. 

B.  Side  view. 

The    post    marked    0   is    connected    with    the    zero    end    of    the    wire    and    the    post    marked 
100   connects   with   the   other  end   of  the   wire. 
S.      Slider  post. 

B.  S.     Bridge  switch. 

C.  Triple  connector. 

I.  S.     Indicator  standard. 

example,  a  reading  of  4  turns  and  7  cap  divisions  would  be  4  x  .20 
ohms  equals  .80  ohms  plus  .07  ohms  equals  .87  ohms. 

The  screw  designated  BS  is  used  as  a  bridge  switch.    When  it  is 
turned  down  it  engages  with  the  thick  brass  connection  attached  to  the 


42 


Rheocord  and  Bridge 


resistance  wire  5  turns  above  the  zero  end.  Thus  a  shorter  length  of 
wire  may  be  used  as  in  taking  telephone  readings  in  conductivity 
measurements  which  is  advantageous  as  a  change  in  sound  may  be 
appreciated  more  sharply.  A  triple  connector  block  is  mounted  upon 
the  base  for  convenience  as  in  resistance  measurements. 


Fig.   36.      Combined   rheocord  and  bridge,   Form   I.     Cross-section. 
» 

Form  II 

In   a   special    form   additional   known   resistance   is   provided   by 
mounting  coils  in  the  base  and  providing  suitable  connections,  Fig.  27 . 


Fig.  37.     Combined  rheocord  and  bridge,  Form  II.     Extra  resistance  is  added  by  mount- 
ing coils  in  the  base  and  providing  suitable  connections.      It  may  be   used   independently. 


CuMBKNUD  KliVS,  KtC. 


43 


Thus  resistance  iij)  to  48  ohms  may  he  used.  The  additional  resistance 
consistint]^  of  42  ohms  is  so  mounted  that  it  may  he  used  independently 
of  the  slider  resistance  in  multiples  of  6  ohms. 

The  construction  is  ru,i;[ged.  There  are  no  loose  parts.  The  sliding 
contact  is  constantly  maintained  and  is  self-cleaning.  It  is  very  efficient 
and  re([uires  little  or  no  attention. 

Combined  Pki.m.\kv  Kkv  and  Skcondarv  Cut-Out  Key,  Switch 

AND  Co M  M  UT  ATOR 

This  ap])aratus  is  compact  and  suhstantially  made.  'J'he  base 
measures  160  mm.  by  110  mm.,  Fig.  38.  There  are  no  concealed  wires 
or  connections,  all  the  conductors  being  flat  metal  strii)s  mounted  on 


Fig.    38.      Combined    primary    key,    secondary    cut-out   key,    switch,    and    commutator.      The 
commutator  attachments  as  in  use  are  shown  by  the  dotted  lines. 
P  and    P'.     Primary   posts. 
S  and   S'.      Secondary  posts.      S  and   S'   may  also  be   used  for  battery  currents. 

the  top  of  the  base.  Essentially  the  primary  key  consists  of  a  movable 
contact,  which  is  a  spring  metal  strip  carrying  the  finger  rest,  and  a 
blunt  cone-shaped  stationary  contact  point  with  which  the  under  sur- 
face of  this  strip  engages.  Platinum  or  other  special  contact  metals 
may  be  apjilied  to  the  contact  surface  and  point,  but  for  ordinary  pur- 
poses this  is  unnecessary,  with  reasonable  care  to  avoid  abuse  of  the 
key  and  if  the  surfaces  are  occasionally  brightened.  Contintious  con- 
tact may  be  maintainecl  by  means  of  the  screw  which  pierces  the 
spring  strip. 


44 


Combined  Keys,  Etc. 


The  switch  consists  of  two  double  spring  keys,  either  of  which 
when  closed  leads  the  secondary  current  from  two  contact  strips  con- 
nected with  the  secondary  coil  to  tissue  electrodes  connected  with  them. 
No  unipolar  stimulating  effects  can  occur  as  contact  with  both  of  the 
leads  from  the  secondary  is  broken  when  the  key  is  released.  The 
contact  points  are  cone  shaped  and  the  surfaces  the  same  as  in  the 


Fig.    39.      Special    form    of   universal    circuit    controller. 


Q  P'On 


a 
o 


oi 


O  r 


Fig.  40.  Diagram  of  universal  circuit  controller.  P,  main  current  leads;  1,  double  slid- 
ing bar;  2,  short-circuiting  contact  bar;  3,  and  3,  4,  switch  contacts  leading  the  current  to 
posts   P'   and   P"   respectively;   3,   4  and  4,   commutator  contacts  leading  current  to  posts   P". 


primary  key.  Each  key  is  provided  with  a  screw  lock  for  maintaining 
contact  when  desired.  When  used  for  single  shocks,  either  closing  or 
opening  shocks  may  be  eliminated  by  closing  the  secondary  keys  before 
or  after  closing  or  opening  the  primary  key,  as  the  case  may  be.  By 
connecting  one  of  the  secondary  keys  to  the  nerve,  and  the  other  to  the 
muscle  electrodes  of  the  myograph.  Fig.  1,  a  muscle-nerve  preparation 
may  be  stimulated  directly  or  indirectly  by  closing  one  or  the  other  of 
the  keys. 


AlToMATIC   CoMHlNKD    KkvS 


45 


To  use  as  a  commutator,  the  attachments  are  connected  to  the 
secondary  keys  as  shown  in  the  figure,  and  the  electrodes  connected 
with  the  attachments.  The  current  is  then  reversed  through  the  elec- 
trodes when  one  or  the  other  of  the  pairs  of  secondary  keys  is  closed. 
Other  currents  may.  of  course,  be  reversed  in  the  same  way  by  con- 
necting to  the  secondary  lead  terminals. 

Combined  Constant   Contact   Primary  and  Automatic 

Secondary  Cut-Out  Keys 

Form  I 

This  is  a  spring  contact  key  operated  by  hand.  Fig.  41.  It  is 
mounted  on  a  wood  base  measuring  140  x  63  x  22  mm.  P  and  P'  are 
binding  posts  connected  with  the  insulated  spring  strips,  P  and  P' 
which  are  provided  with  platinum  contacts.     The  hand,  acting  on  the 


Fig.   41.      Form  I.     Automatic  stimulating  cut-out  key.     Hand  form. 


end  of  the  strip  P,  brings  the  contact  surfaces  of  the  two  springs 
together,  thus  closing  the  primary  circuit.  Between  the  springs  P'  and 
S  is  a  bumper  of  non-conducting  material  B,  so  that  after  the  contact 
between  the  springs  P  and  P'  is  established,  the  force  of  the  hand  is 
communicated  to  spring  S,  which  carries  it  toward  the  base,  thus  bring- 
ing the  platinum  plate  which  it  carries  in  contact  with  the  platinum  con- 
tact point  on  the  spring  S'.  The  force  of  the  hand  continuing  to  act, 
the  end  of  the  spring  S  is  carried  under  the  notch  which  serves  as  a 
catch,  in  the  arm  A,  hinged  to  the  base. 

The  arm  passes  through  a  slot  in  the  spring  P,  and  the  adjustment 
is  such  that  when  the  end  of  the  spring  S  passes  under  the  notch  the 
arm  tilts  forward  in  response  to  a  coil  spring  set  in  the  base,  and  the 
end  of  the  spring  comes  to  lie  in  the  notch.  At  this  time  the  hand  is 
raised,  and  the  pressure  against  the  springs  is  released  in  inverse  order 
to  which  it  was  applied.    Contact  between  P  and  P'  breaks  first.    Fol- 


46 


Automatic  Combined  Keys 


lowing  this,  the  spring  P,  acting  upon  the  cone-shaped,  insulated  upper 
end  of  the  catch  arm,  which  is  tilted  forward,  thrusts  the  arm  to  the 
perpendicular  position,  thus  releasing  S  from  the  catch,  thus  breaking 
contact  between  S  and  S'.  An  adjusting  screw  passes  upward  through 
the  base  and  acts  upon  S'.  Either  closing  or  opening  shock  may  be 
eliminated  by  reversing  primary  and  secondary  connections  with  the 
key.  The  tracing,  Fig.  44,  A,  shows  the  efficiency  of  the  key  both  as 
to  constancy  of  contact  and  elimination  of  secondary  shocks. 


<s=r 


Fig.    42.     Form    II.     Automatic   stimulating   cut-out   key.      Pendulum    form.      Spring   contacts. 

Form  II 

This  is  a  spring  contact  key  operated  by  pendulum,  Fig.  42.  The 
construction  is  essentially  the  same  as  that  of  Form  I.  The  catch  arm 
is  not  provided  with  a  spring,  as  gravity  alone  is  sufficient  to  insure  the 
proper  working  of  the  catch.  A  pendulum  swinging  against  the  pro- 
jecting free  end  of  the  outer  spring  operates  the  contacts.  Tracing, 
Fig.  44,  B,  w^as  taken  with  this  key. 


Mli.tiim.i-:  Dkim   St.wd 
Form  III 


47 


This  i.s  a  mercury  contact  key  operated  by  peiululum,  Fig.  43. 
The  contact  points  P  and  P'  dip  into  mercury  cups  thus  closing  and 
ojicning  the  contact.    Each  point  is  carried  upon  an  axle  and  each  axle 


Fig.  43.     Forrr.  III.     Automatic  stimulating  cut-out  key.     Pendulum  form.     Mercury  contacts. 

is  provided  with  a  spring  trip.  In  addition,  one  axle  is  provided  with 
a  metal  V  through  which  it  is  rocked  back  and  forth  by  a  pendulum. 
The  other  axle  is  equipped  with  a  right  angle  lever  which  is  acted  upon 
by  the  inside  surfaces  of  the  V.  The  adjustment  is  such  that  one  con- 
tact is  made  before  the  other  and  in  opening  the  reverse  occurs.  The 
key  is  employed  as  Form  II.  Tracing,  Fig.  44,  C,  was  taken  with 
this  key. 

Fig.  45  shows  one  form  of  wiring  of  the  above  keys  and  battery, 
coil  and  stimulating  electrodes.  All  of  these  keys  are  well  adapted 
for  use  as  shown  in  Fig.  46  in  place  of  the  electrical  controller. 

Multiple  Drum  Stand 

The  base  is  of  wood,  Fig.  46.  Six  drum  support  rods  are  set  into 
it  perpendicularly.  They  are  spaced  so  that  all  the  drums  may  be 
driven  from  one  belt  as  shown.  The  support  rods  are  sufficiently  tall 
to  permit  the  attachment  of  an  L  support  rod  below  the  drum  sleeve. 
Two  myographs  are  mounted  on  sleeves  on  each  L  rod.  The  myo- 
graphs are  wired  in  series  for  direct  or  indirect  stimulation  or  both. 


48 


Multiple  Drum  Stand 


Fig.    44.     Tracings    taken    with    automatic    cut-out    keys.       In    each    instance    the    current 
was   gradually   increased   and   decreased. 

A.  Hand   form. 

B.  Pendulum  spring  form. 

C.  Pendulum  mercury  form. 


Fig.  45.  Diagram  of  circuits  in  automatic  duplex  keys.  K  and  K',  primary  and 
secondary  keys.  A  pendulum  closes  K'  before  K,  thus  short-circuiting  the  closing  induced 
current. 

K'  is  opened  before  K,  thus  permitting  the  opening  induced  current  to  flow  through  the 
stimulating  circuit,  in  which  the  tissues  are  interposed   in   series. 


Al'To.matic  Mvogkai'u   Kkv 


49 


A  drum  motor  is  used  for  rotalinj,'  llic  drums.  Any  of  tlie  three  forms 
of  combined  constant  contact  primary  and  automatic  cut-out  secondary 
keys  described,  or  the  electrical  current  controller  which  is  shown  in 
Fig.  70  give  satisfactory  results.  The  ai)paratus  is  especially  adapted 
for  studying  the  action  of  solutions.  A  sample  tracing  is  shown  in 
Fisr.  47. 


Fig.    46.     Multiple   drum   stand   and   arrangement    of    ajjparatus    comprising    drums,    motor 
and   belt,   and   myographs.      Wired    in    series   with   the   combined    coil    and   current   controllers. 


RINCER  + 

.i-UiieSuOar 
JST08S  HRS 

TYRODE 

10  TO  II   HRS 

LOCKE 

S   TOG  HRS 

CER^.\CH 

MTOI0  5HRS 


mmmmmm 


m  mwimaimmm^amm  mm  mmm 


Fig.   47.     Tracings    from   multiple   drum   assemblage. 

Automatic  Myograph  Key 

In  principle  the  key,   Figs.  48  and  49,  is  based  upon  Stewart's 
method   of   automatic   stimulation    (Stewart,    Manual   of    Physiology, 


50 


Automatic  Myograph  Key 


1914,  p.  724).  The  contact  points  are  platinum,  and  adjustment  is  such 
that  the  current  may  be  closed  or  opened  at  any  point  of  contraction 
or  relaxation  of  a  muscle  attached  to  the  myograph.  By  means  of  the 
comb,  Fig.  50,  horizontal  lines  are  easily  run  through  the  tracing  and, 


Fig.  48.     Automatic  myograph   key  attached  to  myograph. 


Fig.   49.     Automatic  myograph  key.     Top  and  end  views. 

since  the  teeth  of  the  comb  are  spaced  to  correspond  with  the  divisions 
on  the  head  of  the  screw  by  means  of  which  the  contact  is  adjusted  or 
set,  the  instant  of  closure  or  opening  of  the  circuit  may  be  determmed 
on  the  tracing  with  accuracy  and  ease.  The  indicator  scale  on  the 
screw  may  be  turned  independently  of  the  screw  and,  therefore,  may 
be  readily  set  for  zero. 


DiuM  CiixTKdi.  Stand 


51 


Results  of  a  calibration  test  are  shown  in  Fic^.  51. 
The  effects  of  a  single  stimulus  a])plie(l  to  the  heart  in  varying 
)hases  of   activity   hv   means  of   the  key  are  shown  in  Fig.  52. 


/ 

if 

/' , 

/ 

/ 

^WW""^i 

Fig.    SO.     A   and    B.      Automatic   myograph    key    comb    or    line-marker. 
C  is  a  section  of  the  spacer  for  the  points. 


DiiUM  Control  Stand 

The  stand  serves  as  a  practical  and  accurate  means  of  rotating 
uniformly  and  controlling  the  drum  at  fast  speeds.  Also  it  serves  to 
unite  the  drum  and  apparatus  support  to  a  common  base,  thus  assuring 
optimum  conditions  for  assembling  and  adjusting  recording  apparatus. 
The  entire  assemblage  may  be  moved  without  danger  of  disturbing 
the  adjustments.  The  writing  points  of  recording  instruments  are 
simultaneously  removed  momentarily  or  readjusted  to  the  recording 
surface  by  swinging  the  support  rod  slightly  away  from  or  toward  the 
drum.     Delicate  adjustments  are  easily  and  rapidly  made. 

The  stand  is  provided  with  a  support  rod  for  a  hand  drum  rotator 
and  a  drum  brake,  Fig.  54,  for  controlling  the  drum  at  fast  speeds  and 
for  attaching  the  apparatus  support  stand.  Another  support  rod  is 
provided  for  holding  an  automatic  drum  single  and  double  contact  key, 
which  is  worked  by  a  combined  brake  and  key  pin  attached  to  the 
under  surface  of  the  drum.  This  support  rod  further  serves  for  hold- 
ing other  apparatus  in  certain  experiments.  A  pulley  is  mounted  on 
the  base  and  a  weight  and  cord,  Fig.  57,  are  employed  for  rotating  the 
drum  at  fast  speeds.  A  knot  holder  is  attached  to  the  lower  end  of 
the  sleeve.    The  stand  is  designed  for  the  later  Porter  recording  drum 


52 


Lu 

^ 

La — 

ii   ... 

=^^S==S=SSP====^=========== 

-t — 1 — r — 1 — 1— 

r7t^t3U'.-U'?'r'r'J.,',*'..'., 

f.  'i-/i,  n  If  '"I  J^o  *>  -"-^^  J4-2J  ;>■'«.  7,7  a?i«f  io 

Fig.   51.      Calibration  test   of  automatic   myograph  key.      Drum   turned   with   hand   rotator. 
Figures  beneath  signal  tracing  indicate  screw  turns  in  full  divisions. 


Fig.  52.     Heart  tracing.     Automatic  stimulation.     Ventricle  of  turtle's  heart.     The  dots  on 
the   tracings   indicate   the   point   of   stimulation.      The   signal   tracing  provides   a   check   on   the 

efficiency   of   the   contact. 


DUCM    CilN'TkOI.    t>T.\M) 


53 


models.  With  llic  stand  and  its  attachnuMits  it  is  a  simple  matter  and 
requires  but  little  lime  to  take  aeeurate  traein<,^s  showing  the  phases  of 
a  simple  museular  contraction,  summation  of  stimuli,  superposition  of 
contraction,  rate  of  nerve  im])ulse,  refractory  period,  etc. 


Fig.    53.     Drum   control   stand,    Form    I. 


Form  I 


The  base  of  the  stand  is  of  wood,  blackened  and  wax  finished, 
Fig.  5.S.  It  measures  408  x  176  mm.  and  is  22  mm.  thick.  The  bottom 
surface  is  provided  with  three  foot  pads.  The  upper  surface  is  pro- 
vided with  depressions  for  the  foot  rests  of  the  kymograph  and  two 
attached  clamps  of  nickeled  spring  brass  for  holding  the  kymograph 
base.  At  the  front  margin  is  the  wooden  pulley  support  which  is 
finished  like  the  base.  The  pulley  is  nickeled  brass.  To  one  side  of 
the  pulley  support  is  the  support  for  the  apparatus,  hand  drum  rotator, 
and  drum  brake.  Fig.  54.     Behind  this  at  the  posterior  margin  of  the 


54 


Drum  Control  Stand 


base  is  the  key  support.  Both  supports  are  of  heavy  nickeled  brass 
tubing  screwed  into  bases  of  the  same  material,  which  in  turn  are  firmly 
attached  to  the  wooden  base  bv  heavy  nickeled  brass  screws. 


t 


kza 


5 


Fig.  54.     A.   Drum  rotator;  see  also  Fig.  71.     One  division  of  the  rotator  moves  the  drum 
through  one  milHmetfer. 

B.     Drum  brake;  see  also  Figs.  55  and  1. 

Form  II 


The  base  is  of  compact  form,  Fig.  55.  It  is  made  of  iron  and  is 
given  a  smooth  water-proof  finish.  It  is  provided  with  three  leather- 
soled  feet.  A  rigid  arm  rises  perpendicularly  from  the  back  of  the 
base  and  terminates  above  in  an  adjustable  hinged  extension,  wdiich 
carries  a  pointed  bearing  to  engage  in  a  bearing  socket  in  the  screw  on 
the  upper  end  of  the  drum  sleeve.  Thus,  support  is  given  to  the  free 
end  of  the  spindle,  wdiich  eliminates  excessive  vibration  when  the  drum 
is  checked  and  stopped  at  fast  speeds,  especially  when  heavy  weights 
are  employed.  The  base  weighs  8  pounds,  and  this  further  serves  to 
eliminate  vibration.     The  pulley,  stand  and  key  rod  and  drum  base 


DlU'M    A\n    Co.VTKOI.I.Kk 


55 


clamps  arc  nickeled  hrass.  'J\vo  additional  ijullcys  may  be  mounted  on 
the  perpendicular  arm,  one  near  the  base  and  the  other  at  the  top  so 
that  it  is  not  necessary  for  the  front  pulley  to  j)roject  beyond  the 
edge  of  the  table,  but  for  ordinary  purposes  the  additional  ])nlleys  are 
superfluous. 


Fig.    55.     Drum   control   stand.    Form   II. 


Recording  Drum  and  Controller 

The  drum,  Fig.  56,  is  mounted  on  a  substantial  cast  iron  base.  It 
is  driven  by  a  weight  and  cord,  Fig.  57.  Any  speed  from  a  few  milli- 
meters per  minute  to  500  or  more  per  second  is  easily  and  quickly 


56 


Drum  and  Controller 


attainable.  All  speeds  may  be  regulated  by  the  weight.  In  addition, 
the  slower  speeds  are  controlled  by  a  viscosity  brake.  The  spindle 
and  brake  pulley  comprise  a  single  moving  part.  The  construction 
throughout  is  rugged  and  designed  for  heavy  service.  The  design 
is   such  that   little  time   is   required    for   dismounting,   assembling  or 


Fig.    56.     Recording  drum  and  controller. 


adjusting.  Simple,  strong,  and  efficient  attachments  are  provided  for 
all  ordinary  needs.  The  tubular  posts  arising  from  the  base  provide 
a  means  of  attaching  a  hand  drum  rotator  and  drum  brake  for  high 
speed  work,  Fig.  54,  and  a  drum  stimulating  key,  Fig.  30.  To  the 
anterior  of  these  posts  is  attached  a  universally  adjustable  recording 


Dkl:M    AM)    CdXTUdl.l.KR 


57 


apparatus  stand,  thus  cliniinatini:^  the  need  of  separate  apparatus  sup- 
ports. The  base  is  smoothly  finished  in  l)lack  and  all  brass  ])arts  are 
nickeletl. 

The  drum  itself  is  of  the  Porter  east  aluminum  pattern.  It  is 
mounted  on  a  sleeve  support,  Fig.  59,  to  which  it  is  fixed  at  any  height 
by  a  substantial  lock  on  the  U])per  end.  It  is  prevented  from  turning 
by  a  key  on  the  sujiport  and  a  slot  in  the  lower  end  of  the  drum.     Thus 


Fig.    57.     Weight   and   cord.      The   weight   unscrews   in   the   middle,   the   connector   i)in    re- 
maining with   the  lower  half. 


Fig.    58.     A.      Swinging   arm   and   upper   liearing.      B.    Anterior   pulley    support. 
Measurements  are  in  millimeters. 


accidental  moving  or  creeping  of  the  drum  in  any  direction  on  the  sup- 
port is  guarded  against.  Yet  it  is  instantly  adjustable  to  any  horizontal 
or  perpendicular  plane.  A  combined  drum  brake  and  key  pin  is  set, 
with  insulation,  in  the  lower  end  of  the  drum.  The  drum  is  mounted 
on  the  spindle  of  the  controller.  The  drum  support  is  tubular  brass, 
Fig.  60,  A.  The  upper  end  is  closed  and  inside  it  is  provided  with  a 
centered  cone  pointed,  hardened  steel  bearing  which  bears  on  the  upper 
end  of  the  controller  spindle.  This  bearing  carries  the  weight  of  the 
support  and  drum.  The  outer  surface  of  the  closed  upper  end  of  the 
support  is  provided  with  a  centered  socket  in  hardened  steel  to  receive 


58 


Drum  and  Controixi'.r 


the  drill  steel  pin  of  the  upper  controller  bearing.  The  inside  diameter 
of  the  support  is  somewhat  greater  than  the  diameter  of  the  controller 
spindle  and  near  the  upper  end  a  brass  ring  bearing  is  provided,  which 
is  accurately  fitted  and  adjusted  to  the  spindle,  which  is  drill  steel,  so 
that  the  drum  may  turn  smoothly  and  not  have  undue  "p^^y-"     The 


Fig.   59.      Drum  mounted   on  sleeve. 


Fig.    60.     A.   Drum   support   sleeve. 


Reel. 


C.   Spindle. 


lower  end  of  the  support  is  open.  To  the  outer  surface  near  the  lower 
end  is  affixed  an  encircling  brass  friction  band.  It  is  acted  upon  by  the 
friction  arm  and  screw  of  the  reel,  and  thus  the  support  and  reel  are 
united  with  any  desired  degree  of  rigidity.  The  end  of  the  support 
below  the  friction  band  fits  accurately  into  a  circular  slot  in  the  upper 
end  of  the  reel  and  serves  to  aid  in  centering  and  maintaining  the  two 


Drum  an'd  Controf.i.kr  59 

in  position.  The  wall  around  the  lower  end  of  the  support  is  beveled 
on  l)oth  sides  to  insure  its  entering  the  slot  smoothly  without  special 
attention  when  the  support  is  placed  on  the  spindle.  The  length  of  the 
drum  support  is  ample  to  provide  for  all  perpendicular  adjustments 
of  the  drum,  and  for  smoking  the  drum  paper  without  soiling  or  burn- 
ing the  hands. 

The  reel,  Fig.  60,  B,  carries  the  weight  cord  and  transmits  the 
turning  force  to  the  drum.  It  is  of  tubular  brass  of  the  same  trans- 
verse dimensions  as  the  drum  suj)port.  Inside,  near  cither  end,  it  is 
provided  with  circular  bearings  accurately  fitted  to  the  controller 
spindle  like  that  of  the  support.  The  upper  end  is  provided  with  a 
slot  to  receive  the  lower  end  of  the  drum  support.  Also  it  carries  a  self- 
adjusting  friction  lock  for  connecting  the  reel  and  drum  support.  Owing 
to  the  extensive  and  accurate  engagement  of  the  lower  end  of  the  drum 
support  and  the  slot  in  the  reel  and  the  self-adjusting  feature  of  the  fric- 
tion lock,  the  pressure  of  the  friction  arm  and  of  the  screw  to  the  oppo- 
site points  of  the  friction  band  of  the  drum  support  is  equalized  and 
there  is  no  danger  of  causing  the  reel  and  drum  support  bearings  to  bind 
on  the  controller  spindle  when  the  two  are  locked  together.  The  blunt 
cone  point  of  the  locking  screw  centers  on  the  beveled  surface  of  the 
friction  band,  and  as  this  surface  is  on  the  upper  margin  of  the  band, 
the  reel  and  drum  spindle  are  drawn  tightly  together  end  to  end  when 
the  screw  is  tightened,  thus  causing  end  as  well  as  side  pressure  at 
the  joint. 

A  heavy  collar  is  affixed  to  the  lower  end  of  the  reel.  In  this,  a 
knot  holder,  consisting  of  a  pin  terminating  in  two  blunt  parallel  arms 
is  set  for  instantly  attaching  the  weight  and  cord  to  the  reel. 

The  collar  also  carries  a  set  screw  for  locking  or  releasing  the  reel 
from  the  controller  spindle.  A  stop  in  the  form  of  a  collar  on  the 
spindle.  Fig.  63,  prevents  the  reel  from  being  set  at  so  low  a  level  that 
an  imperfect  connection  with  the  drum  support  might  cause  binding 
of  the  bearings  on  the  spindle. 

The  drum  is  removed  from  the  controller  by  (1)  locking  the  reel 
to  the  spindle;  (2)  unlocking  the  drum  support  from  the  reel;  (3) 
turning  the  hinged  upper  bearing  arm  upward  and  backward;  (4)  lift- 
ing the  drum  support  (or  sleeve)  wdth  the  drum  ofif  the  controller 
spindle.  To  mount  the  drum,  the  processes  are  reversed.  To  wind  the 
reel,  the  drum  is  mounted  and  locked  to  the  reel.  The  reel  is  then 
unlocked  from  the  spindle,  the  cord  of  the  weight  placed  over  the  pulley 


60  Drum  and  Controller 

with  the  weight  suspended  and  the  knot  at  the  end  of  the  cord  placed 
in  the  holder  and  the  drum  rotated  backward,  i.  e.,  anti-clockwise  until 
the  weight  is  raised  near  to  the  pulley,  when  the  reel  is  locked  to  the 
spindle.  The  drum  is  conveniently  rotated  by  manipulating  the  upper 
end  of  the  reel  with  the  fingers  of  one  hand.  The  cord  should  be 
evenly  wound.  This  is  insured  by  slightly  depressing  or  raising  it 
between  the  reel  and  pulley  if  necessary.  The  weight  provides  an  even 
tension  during  winding. 

For  slow  and  moderate  speeds,  i.  e.,  up  to  30  to  50  millimeters  per 
second,  the  viscosity  brake  is  used.  Therefore,  the  reel  remains  locked 
to  the  controller  spindle  and  the  drum  is  started  and  stopped  by  releas- 
ing and  clamping  the  spindle.  The  rate  of  the  spindle  is  adjusted  by 
the  speed  regulator,  or  by  increasing  or  decreasing  the  weight,  or  both. 

For  faster  drum  speeds,  the  drum  and  reel  lock  is  released  until 
the  joint  turns  freely  and  the  milled  surface  of  the  drum  stop  pin  is 
adjusted  to  the  drum  brake  and  stop.  The  drum  sleeve  and  reel  are 
then  relocked  together  and  the  reel  released  from  the  controller  spindle. 
When  released  by  the  brake  and  stop,  the  drum  and  reel  rotate  inde- 
pendently of  the  controller  spindle,  %.  e.,  they  rotate  around  it  owing  to 
the  inside  support  bearing  at  the  top  of  the  sleeve  which  carries  the 
weight  on  the  end  of  the  spindle,  and  the  three  inside  ring  bearings. 
The  drum  is  steadied  and  with  the  spindle  is  held  perpendicular  by  the 
socket  in  the  top  of  the  sleeve  and  with  the  pin  carried  by  the  hinged 
arm  of  the  rigid  support  rising  from  the  controller  base. 

For  stationary  work,  that  is,  when  records  are  made  as  perpen- 
dicular lines,  the  drum  being  turned  slightly  between  such  records,  the 
reel  is  locked  to  the  spindle  and  the  drum  sleeve  released  from  the  reel. 
If  the  drum  is  turned  by  hand  enough  friction  may  be  maintained  in 
the  joint  as  may  be  desirable  to  insure  the  immobility  of  the  drum  while 
records  or  notes  are  being  written  on  the  smoked  surface.  If  rotation 
is  by  means  of  the  hand  rotator.  Fig.  54,  A,  the  sleeve-reel  lock  is 
completely  released  and  the  sleeve  raised  slightly  in  the  drum  (say  one 
millimeter),  so  that  the  weight  may  be  carried  by  the  rotator,  thus 
insuring  its  proper  action. 

The  controller  spindle,  Fig.  60,  C,  is  of  drill  steel.  The  upper  end 
is  free  when  the  drum  sleeve  is  removed.  When  the  drum  is  mounted 
the  upper  end  forms  a  bearing  with  the  inside  cone-pointed  bearing  of 
the  sleeve  and  it  is  centered  to  the  pin  of  the  upper  outside  bearing, 


DkLM    and    CoNTROl.I.KR 


61 


that  is,  the  bearing  between  the  socket  in  the  upper  surface  of  the  end 
of  the  drum  sleeve  and  the  pin  carried  by  the  hinged  arm  of  the  upper 
I)earing  support,  through  the  ring  bearings  in  the  drum  sleeve  and  reel. 
The  lower  end  of  the  spindle  is  cup])ed  and  rests  upon  a  hardened 
steel  ball,  which  is  set  in  a  socket  in  the  floor  of  the  viscosity  chamber 
of  the  controller  base.  Fig.  61.     The  ball  rests  ujjon  a  hardened  steel 


Fig.  61.  Cross-section  of  base  of  drum  stand.  Note  the  lower  bearing,  the  viscosity 
chamber,  pulley  and  brake,  the  air  chamber  of  the  cap  communicating  with  viscosity  chamber 
through  a  hole  in  the  diaphragm,  and  the  double  grease  cup  seal  in  the  air  chamber.  The 
leather  soles  of  the  drum  feet  are  shown. 

floor.  The  socket  is  provided  above  with  a  narrow  circular  brass  bear- 
ing surface,  which  is  fitted  to  the  lower  end  of  the  spindle.  Just  above 
the  lower  bearing  the  spindle  carries  a  brass  oval- faced  pulley,  which  is 
set  rigidly  to  the  spindle,  after  which  the  outer  face  is  turned  and 
polished  very  accurately,  as  it  is  by  means  of  this  surface  that  the  speed 


OJrEi: 


Fig.   62.     Diaphragm   interposed   between   viscosity   and   expansion   chamber.      Note   lower 
half  of  grease  seal  and  hole  for  expansion  of  glucose. 


of  the  spindle  is  regulated.  Above  the  pulley  the  spindle  passes  through 
a  metal  diaphragm.  Fig.  62,  but  does  not  come  into  contact  with  it, 
excepting  through  a  grease  cup  seal  on  the  upper  surface  of  the  dia- 
phragm. Passing  upward  the  spindle  emerges  from  the  viscosity 
chamber  cap  but  does  not  form  contact  with  it  save  through  another 
grease  cup.     It  then  passes  through  the  garrotte  clamp.  Fig.  63,  by 


62 


Drum  and  Controller 


means  of  which,  at  viscosity  speeds,  the  drum  is  started  or  stopped. 
Just  above  this  point  the  spindle  carries  the  narrow  circular  stop  for 
limiting  the  position  of  the  reel. 


Fig.  63.     Top,  side  and  bottom  view  of  spindle,  viscosity  chamber  cap,  and  brake.     To  the 
right  is  a  top  view  of  the  clamp   for  stopping  the  drum. 

The  spindle  has,  therefore,  two  bearings,  the  upper  being  of  the 
pin  and  socket  type,  the  lower  being  of  a  combined  ball  end  thrust  and 
annular  side  type.  The  ball  end  bearing  carries  all  of  the  load  and  is 
subjected  to  the  severest  duty  of  any  of  the  bearings,  but  it  is  capable 
of  sustaining  many  times  as  much  strain  as  can  be  exerted  upon  it 
through  the  use  to  which  it  is  here  put  without  danger  of  appreciable 
wear  or  damage.  The  edge  bearing  surface  of  the  annular  part  of  the 
lower  bearing  has  only  to  withstand  the  pull  of  the  weight  which  is 
applied  to  the  spindle  at  the  level  of  the  reel,  and  this  only  at  the 
viscosity  speeds.  Therefore,  it  is  subjected  to  but  little  wear.  At  fast 
speeds,  that  is,  when  the  drum  is  rotated  upon  the  spindle,  the  garrotte 


Drum  and  Controli.kr 


63 


clamp  rigidly  holds  the  spindle  and  thus  relieves  the  lower  hearing  of 
all  duty.  All  hearings  possess  a  very  large  margin  of  surplus  strength 
and  are  capahle  of  unlimited  usage  without  material  wear.  Occasion- 
ally a  drop  of  oil  or  a  very  little  vaseline  should  he  applied  to  the  top 
and  side  of  the  sj)indle  and  to  the  outside  top  hearing  to  insure  con- 
stancy of  rate  at  high  speeds,  hut  no  appreciahle  damage  will  result 
from  failure  to  do  this.  Of  course,  if  the  parts  are  allowed  to  rust, 
perfect  performance  cannot  he  expected. 


Fig.    64.     Drum   viscosity   brake.      Dismounted   to   sliow   construction.      The    regulator   is 
shown  below. 

The  speed  of  the  spindle  is  regulated  through  the  viscosity  brake, 
Fig.  64,  and  hy  means  of  the  weight.  The  brake  pulley  is  embraced 
at  opposite  points  of  its  face  by  brake  shoes  faced  with  wool  yarn. 


iajjJjJ4dtJiliil|iJiiJiiijaijmilf(llll(flllliUUiiiiliitlllJ:^ 


Fig.  65.  Drum  test.  The  upper  four  tracings  are  of  a  Jacquet  time  marker  recording 
seconds  on  a  drum  controlled  with  a  viscosity  brake.  The  speed  may  be  set  for  one  revolu- 
tion in  30  minutes  or  longer.  By  adding  weight  a  much  faster  viscosity  regulated  speed  than 
that   shown   in   the    fourth   tracing   may   be   obtained. 

The  two  tracings  at  the  bottom  are  of  a  tuning  fork  giving  100  D.  V.  per  second.  The 
drum  sleeve  rotated  on  the  spindle.  A  wide  range  of  speed  may  be  obtained  by  this  method 
by  altering  the  weight. 


64 


Automatic  DuplKx  Circuit  Controller 


The  yarn  is  wrapped  transversely.  The  faces  of  the  shoes  next  to  the 
pulley  are  doubly  concave,  so  the  yarn  surface  that  acts  upon  the  pulley 
is  elastic  as  it  extends  between  the  edges  of  the  horizontal  concavity. 
Also,  this  permits  of  automatic  adjustment  of  each  yarn  strand  to  the 
pulley  without  binding  and  insures  an  even  and  constant  distribution 
of  glucose  to  the  surface,  the  cavity  between  the  yarn  and  metallic  sur- 
faces being  occupied  by  this  substance.  The  shoes  are  mounted  on  a 
pair  of  self-adjusting  U-arms.  The  arms  are  approached  or  separated 
by  a  quadrant  lever  and  calibrated  screw  on  top  of  the  base  which  are 
provided  with  indicator  scales.  The  faces  of  the  brake  shoes  but 
lightly  come  into  contact  with  the  polished  pulley  face,  and  wear  at  this 
point  is  practically  a  negligible  factor,  but  the  lever  is  adjustable  so 
any  material  wear  is  easily  compensated. 


Fig.  66.  Tests  of  drum'for  uniformity  of  rate  at  fast  speeds.  The  test  was  made  with 
one  winding  of  the  weight  cord.  Especial  care  was  not  exercised  in  the  experiment.  The 
results  would  indicate  a  variation  of  only  a  few  per  cent.  When  such  possible  error  is  con- 
sidered as  in  measuring  a  tracing  for  latent  period,  it  becomes  practically  negligible.  (Cf. 
Figs.  33  and  34.) 


The  viscosity  chamber  is  filled  with  glucose  and  covered  with  a 
metal  diaphragm  to  insure  uniform  action  of  the  glucose  on  the  pulley. 
The  diaphragm.  Fig.  62,  is  of  cast  brass  and  provided  with  a  grease 


AlTDMATIC    Dl'IM.KX    ClKCL'lT    CoNTUOI.I.KR  C)5 

cup  seal  surrouiulint;-  the  s])iii(llc.  It  is  fastened  to  the  upjjer  surface  of 
the  viscosity  chanil)er  cover,  and  separates  the  viscosity  chamber  below 
from  the  air  chamber  of  the  cap  above,  except  for  a  small  hole  in  the 
diaphragm,  which  serves  as  an  expansion  outlet  for  the  glucose.  Vis- 
cosity changes  due  to  temperature  variations  introduce  no  practical 
difficulties,  as  such  changes  are  so  slight  during  the  course  of  an  or- 
dinary experiment  as  to  be  negligible.  For  special  use,  a  temperature 
compensating  attachment  may  be  introduced.  The  results  shown  in 
Figs,  65,  66,  68,  72,  33,  34,  51,  52,  etc.,  give  a  good  idea  of  the  efficiency 
of  the  drum  under  various  conditions. 

Combined  Priiniarv  and  Secondary   Circuit  ControllivR 

The  controller.  Fig.  67,  automatically  performs  the  following 
operations : 

1.  Closes  and  opens  the  primary  circuit  at  any  rate  from  one  per 
minute  to  100  per  second. 

2.  Makes  uniform  closing  contacts  and  opening  interruptions. 

3.  Eliminates  closing  or  opening  secondary  currents  or  permits 
both  to  flow  through  the  electrode  circuit. 

The  controller  is  actuated  by  an  electro-magnet.  The  rate  of  in- 
terruption is  regulated  by  an  oil  brake  and  is  readily  adjustable.  Uni- 
form electrical  contact  is  made  by  a  coil  spring  acting  eccentrically  on 
a  rocking  arm  bearing  a  contact  surface.  All  parts  are  adjustable. 
The  contact  period  is  short,  being  under  0.03  second  at  slow  speeds  and 
less  at  rapid  speeds.  The  contact  is  opened  by  the  movement  of  the 
magnet  bar  in  response  to  the  pull  of  the  magnet.  No  special  retarding 
force  is  opposed  to  the  movement.  The  oil  brake  retards  closure  of 
the  contact.  It  recjuires  one  to  two  amperes  of  current.  One  or  two 
dry  batteries  are  adequate.  When  used  with  an  induction  coil  they  are 
wired  in  series. 

The  secondary  controller  is  operated  from  the  same  magnet.  It 
automatically  short-circuits  the  secondary  before  closure  of  the  primary 
contacts,  and  breaks  the  short-circuit  while  the  primary  circuit  is 
closed.  It  is  connected  in  parallel  with  the  secondary  circuit.  It  is 
easy  to  extend  the  short-circuit  attachment  so  that  it  may  be  adjusted 
for  eliminating  either  opening  or  closing  shocks. 


66 


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Fig.   68.     Primary   interrupter  test. 

Tracings  1  to  7,  inclusive,  taken  with  electro-magnetic  signal;  tracing  8,  Jacquet  time- 
marker  set   for  seconds.      Drum   speed  was  the   same   for   all   tracings. 

Same  as  A,  only  tracing  7  is  by  Jacquet  time-marker  set  for  seconds. 

Primary  interrupter  set  for  seconds  with  periodic  groups  of  rapid  interruptions  controlled 
at  will.  Thus  used  it  serves  as  a  base  line,  time,  and  signal  recorder.  The  induced 
current  during  periods  of  rapid  interruption  may  be  led  to  stimulating  electrodes  by 
means   of  the  secondary   hand  key. 

Automatic  periodic  grouping  of  interruptions  with  control  of  time  between  periods  and 
number  and  rale  of  interruptions  in  each  period  obtained  by  connecting  two  inter- 
rupters. 


68 


CoMiuNED  Coil  and  Current  Controllers 


The  mechanism  is  substantially  constructed  and  is  very  durable. 
It  is  easy  to  adjust  and  requires  very  little  attention.  It  closes  and 
opens  the  circuit  in  a  uniform  manner  and  is  easily  adjusted  while  in 
operation  for  any  rate  from  one  per  minute  or  slower  to  100  contacts 
and  interruptions  per  second.  With  a  battery  and  signal  it  may  be  used 
as  a  time  marker ;  or  connected  in  the  primary  circuit  of  an  induction 
coil,  to  open  the  circuit  uniformly  to  closure  with  a  hand  key,  or  to 
both  close  and  open  the  circuit  automatically  at  any  rate  desired  within 
the  limits  mentioned.  Fig.  68. 


Fig.    69.     Myograms   illustrating   cut  rent   control    with    the    interrupter   and    rheocord. 


Combined  Coil,  Current  Controller,  Rheocord,  Primary  and 
Secondary  Keys,  Switch  and  Commutator 
(Combined  Coil  and  Current  Controllers) 

The  various  parts  of  this  apparatus.  Fig.  70,  are  mounted  on  a 
three-ply  wooden  base  measuring  223  x  190  x  16  mm.  At  the  back  the 
base  projects  upward  75  mm.     Upon  the  upper  edge  of  the  back  are 


CoMlilNKO   Coil.    AN!)    ClKKKNT    Co.NTKdl.l.KRS 


69 


mounted  the  primary  and  secondary  l)inding  posts.  The  primary 
ilivision  of  the  circuit  controller  is  connected  in  ])arallel  through  the 
primary  hand  key  with  the  rheocord  and  coil.  The  rheocord  may  be 
removed  from  the  circuit  by  means  of  a  contact  screw.  It  may  be 
so  mounted  that  it  can  be  used  indej)endently  of  the  other  parts  of  the 
apparatus.     The  coil  is  of  the  Porter  form.     The  core  of  the  primary 


Fig.   70.     Combined  coil  and  current  controllers. 


may  be  removed.  The  secondary  may  be  raised  perpendicularly.  The 
finer  degrees  of  the  stimulating  current  are  obtained  with  the  rheocord. 
The  secondary  leads  are  connected  with  the  secondary  key  leads  and 
with  the  secondary  division  of  the  current  controller.  The  circuit  may 
be  broken  to  the  controller  by  means  of  a  contact  screw.  Also,  the 
circuit  to  the  keys  may  be  broken  by  another  contact  screw^  By  opening 
both  these  screws  the  secondary  keys  are  isolated,  so  they  may  be  used 
for  a  battery  current.  A  pair  of  binding  posts  on  the  key  leads  serves 
for  such  connection.  Commutator  connectors  (see  Fig.  38)  are  pro- 
vided.   When  not  in  use,  they  are  attached  to  the  back  side  of  the  base. 


1 


70 


Combined  Coil  and  Current  Controllers 


In  Fig.  71  the  apparatus  is  shown  in  use  with  the  drum.     The 
tracing  shown  in  Fig.  72  was  taken  in  this  manner. 


Fig.  71.     Dnnn,  myograph,  signal,  and  combined  coil  and  current  controllers. 


Fig.   72.     Myogram  taken  with  apparatus  as  shown  in  Fig.  71. 


Fig.   13.      Drum  and  attachments  and  accessories  in   case. 


Fig.   74.     Drum  case  closed.     It  measures  8J^  x  11  x  20  inches. 


PRESS    OF 
KOHN   AND   POLLOCK,   INC. 

BALTIMORE 


COLUMBIA   UNIVERSITY 

This  l)C)ok   is  due  on  the  date  indicated  below,  or  at  the 
expiration  of  a  definite  period  after  the  date  of  borrowing, 
as  provided  by  the  rules  of  the  Librarj'  or  by  special  ar- 
rangement with  the  Librarian  in  charge. 

DATE  BORROWED 

DATE  DUE 

DATE  BORROWED 

DATE  DUE 

C2e(63e>M50 

Civ.thrie 


